Calculate the Median Value
-- Median
SELECT
(
(SELECT MAX([Total Debt]) FROM
(SELECT TOP 50 PERCENT [SALES] FROM dbo.Data ac WHERE FIleDate = '20170306' ORDER BY [ac].[Sales] ) AS BottomHalf)
+
(SELECT MIN([Total Debt]) FROM
(SELECT TOP 50 PERCENT [SALES] FROM dbo.Data ac WHERE FIleDate = '20170306' ORDER BY [Sales] DESC) AS TopHalf)
) / 2 AS Median