FINE, J.

¶ 1 Farmers Insurance Exchange and its insured, Cindy L. Close, appeal the judgment awarding damages to Rene Correa for injuries a jury found he sustained as a result of an automobile accident with Close. They also appeal the trial court's order denying their postverdict motion. The only issue on appeal is whether there was sufficient evidence to support the jury's award of $30,000 for Correa's "[p]ast hospital and medical expenses." We affirm the judgment and order in part, and remand for further proceedings.

¶ 2 Farmers Insurance and Close do not dispute that there was evidence during the trial that Correa had past hospital and medical expenses. They contend, however, that no one with the requisite expertise testified that the charges were "reasonable." The trial court upheld the verdict's award, ruling that the jury could infer that they were reasonable: "[T]he question was not asked was the dollar amount of the bills reasonable and necessary, but I think the total of the testimony, I think that's something based upon the cumulative wisdom of the jury. I think they can make the inference and make a decision."

¶ 3 The rule, of course, is that an injured plaintiff may only recover the value of medical expenses he or she incurred, "`not the actual charge'" if they differ. Leitinger v. DBart, Inc., 2007 WI 84, ¶ 23, 302 Wis.2d 110, 121-122, 736 N.W.2d 1, 6 (quoted source omitted). As shown below, before July 1, 2009, this value could only be proved by expert testimony. See Dean Medical Center, S.C v. Frye, 149 Wis.2d 727, 733, 439 N.W.2d 633, 635 (Ct.App. 1989) ("A physician must establish necessity of the medical treatment furnished and the reasonableness of charges for that treatment."). Thus, "inference" does not cut it.

¶ 4 The trial in this matter started on August 17, 2009. By that time, WIS. STAT. RULE 908.03(6m), as material here, read as follows:

Under RULE 908.03(6m)(bm), a party desiring to prove the reasonableness of a medical expense need no longer have a qualified expert so testify, provided that the bills are "patient health care records." Although this rule was in effect during the trial, neither the lawyers nor the trial court referenced it. Under applicable standards, though, we may affirm a circuit court for any reason, even if not relied on by either the circuit court or raised by the lawyers. State v. Butler, 2009 WI App 52, ¶ 15, 317 Wis.2d 515, 527-528, 768 N.W.2d 46, 51-52. We ordered the parties to supplement their briefs to address whether the bills reflecting Correa's past medical expenses were: (1) received into evidence, and (2) were "patient health care records" so as to trigger the presumption.

¶ 5 Before we address those matters, we turn to the contention by Farmers Insurance and Close that because the accident was in January of 2004, application of WIS. STAT. RULE 908.03(6m)(bm) would be improperly retroactive. It would not. As long as changes in evidence rules do not alter the elements of a claim or a defense, trials are governed by the rules of evidence as they are at the time of trial. Frame v. Plumb, 138 Wis. 179, 189-190, 118 N.W. 997, 1001 (1908). See also Hopt v. People, 110 U.S. 574, 590, 4 S.Ct. 202, 28 L.Ed. 262 (1884) (criminal case), limitation on other grounds recognized by Illinois v. Allen, 397 U.S. 337, 342-343, 90 S.Ct. 1057, 25 L.Ed.2d 353 (1970), and Carmell v. Texas, 529 U.S. 513, 544-553, 120 S.Ct. 1620, 146 L.Ed.2d 577 (2000) (discussing and distinguishing Hopt and the Ex Post Facto Clause). Correa's entitlement to recover his past medical expenses was the same before and after the amendments to RULE 908.03(6m). Stated another way, the amendments did not change Farmers Insurance's and Close's potential for liability as a result of the accident; the amendments merely fine-tuned how admissible evidence could be established. RULE 908.03(6m)(bm) applies. We now look at the evidence supporting the jury's verdict for past medical expenses.

¶ 6 In order to uphold a jury's verdict there must be some properly admitted evidence that supports it. See Sievert v. American Family Mut. Ins. Co., 180 Wis.2d 426, 433, 509 N.W.2d 75, 79 (Ct. App.1993), aff'd, 190 Wis.2d 623, 528 N.W.2d 413 (1995). Thus, the jury's $30,000 award for past medical expenses may only be upheld to the extent of that supporting evidence, if any. Given that no properly qualified expert witness testified that the charges supporting Correa's claim for past medical expenses were reasonable for the services they covered (although there was expert evidence that the services he received were both necessary and reasonable), application of WISCONSIN STAT. RULE 908.03(6m)(bm) is the only way that part of the verdict may be sustained.

¶ 7 As we have seen, WISCONSIN STAT. RULE 908.03(6m)(bm) creates a presumption that: "[b]illing statements or invoices that are patient health care records are presumed to state the reasonable value of the health care services provided." As material, under WISCONSIN STAT. § 146.81(4), "`[p]atient health care records' means all records related to the health of a patient prepared by or under the supervision of a health care provider; and all records made by an ambulance service provider, as defined in s.256.01(3)."2

¶ 8 Whether the documents asserted to support the jury's award for Correa's past medical expenses are "patient health care records" requires that we apply the rule to those documents. This presents an issue of law. See State v. Booker, 2006 WI 79, ¶ 12, 292 Wis.2d 43, 54, 717 N.W.2d 676, 681. We may not, however, find facts. See Wurtz v. Fleischman, 97 Wis.2d 100, 107 n. 3, 293 N.W.2d 155, 159 n. 3 (1980). Based on the parties' responses to our order directing them to supplement their briefs, we conclude that the following documents were received into evidence and have the following effect under WIS. STAT. RULE 908.03(6m)(bm):

Although it is clear that the document from Milwaukee Neurological Institute, SC, is, under Hart's analysis, a "patient health care record[-]," and that the "Medicaid Claims" documents are not, we cannot on this Record assess whether the entity Milwaukee Occupational Medicine is either "[a] corporation or limited liability company of any providers specified under pars. (a) to (hp) that provides health care services," WIS. STAT. § 146.81(1)(j), or "[a] partnership of any providers specified under pars. (a) to (hp)." WIS. STAT. § 146.81(1)(i). Accordingly, we must remand this matter to the circuit court for fact-finding on this issue. If, on the remand, Farmers Insurance and Close contend that they can rebut the presumption created by RULE 908.03(6m)(bm), see WIS. STAT. RULE 903.01, they should present to the circuit court a specific offer of proof, see WIS. STAT. RULE 901.03(2). If the circuit court finds the offer of proof sufficient, it shall hold an evidentiary hearing, with or without a jury as within its discretion it deems fit. See WIS. STAT. RULE 906.11.

¶ 9 In sum, unless the circuit court finds that the presumption in WIS. STAT. RULE 908.03(6m)(bm) has been rebutted, it shall modify the verdict award for "[p]ast hospital and medical expenses" to include: (1) the ambulance bill for $506.67; (2) the bill of Milwaukee Neurological Institute, SC, for $850.94; and (3) if Milwaukee Occupational Medicine is an entity as defined by either WISCONSIN STAT. § 146.81(1)(i) or WISCONSIN STAT. § 146.81(1)(j), the amount reflected on its compilation of charges. We affirm the judgment and order in part, and remand for further proceedings consistent with this opinion.4

Judgment and order affirmed in part, and cause remanded with directions.