Report on Sprint Percent Complete

We'd like to have the ability to report on the percent complete at the end of each iteration (before incomplete tasks are moved), so that we can see this data for all iterations in a given time period on one page. Currently, the only way to see this data is to click through each iteration on the Story Board page. If you report on Percent Complete in an iteration report, it shows the current percent complete (based on the tasks still in the sprint at the time of viewing the report) rather than the percent complete on the end date of each sprint (which is what we'd like to see).