Je le ferais avec un CTE :
WITH Result AS
(
SELECT Row_Number() OVER (PARTITION BY ItemId, Year
ORDER BY ItemversionId DESC) AS RowNumber
,ItemId
,ItemversionId
,Year
,Value
FROM table
)
SELECT ItemId
,ItemversionId
,Year
,Value
FROM Result
WHERE RowNumber = 1
ORDER BY ItemId, Year