How do I query based on percentages of a subset of values?
WITH  RequiredAmounts
        AS ( SELECT 'A' AS [TYPE] ,
                    200 AS Amount
             UNION ALL
             SELECT 'B' ,
                    200
           )
  SELECT  t.*
  FROM    RequiredAmounts
          CROSS APPLY ( SELECT TOP ( RequiredAmounts.Amount )
                                *
                        FROM    YourTable AS t
                        WHERE   t.[TYPE] = RequiredAmounts.[Type]
                      ) AS t


RequiredAmounts can select from a temporary table, table variable, a TVP. It can be anything. Just replace this sample CTE with whatever suits your needs.