如何使用MDX语句计算度量值比例时，无法计算行列汇总的比例

MDX语句如下所示：
     WITH MEMBER [Product].[ByCategory].[ColTotal] as SUM({[Product].[ByCategory].[Family]})
   MEMBER [Time].[YQMD].[RowTotal] as SUM({[Time].[YQMD].[Year]})
   MEMBER [Measures].[BL] as '[Measures].[Unit Sales]/([Measures].[Unit Sales],
       [Time].[YQMD].CurrentMember.Parent,[Product].[ByCategory].CurrentMember.Parent)',
       SOLVE_ORDER=1,FORMAT_STRING='0.00%'
Select {[Time].[YQMD].[Year].Members,[Time].[YQMD].[RowTotal]} on columns,
   {[Product].[ByCategory].[Family].Members,[Product].[ByCategory].[ColTotal]} on rows
   from Sales
   where {[Measures].[BL]}
结果如下：