I've been thinking. I can just filter on the date, so the later elements in my database wouldn't be considered, but how do I select the "Contract Value" where the "Date" is the maximum?
If custom SQL doesn't destroy performance, then you could use a subquery like this:
SELECT * FROM [Sheet1$] d WHERE d.[Date] = ( SELECT MAX(d2.[Date]) FROM [Sheet1$] d2 WHERE d2.[Date] <= <Parameters.Parameter 1> )
See more in attached workbook.