当在另一列中计算第 50 个百分位时，仅在列中显示一个值

Question

我正在查询这样的表：

HerdID   Event
100      01/01/2009
100      08/01/2009

有多个 HerdID，事件发生多年，一年内每个 HerdID 有多个事件。 我对每年每个牛群发生的事件的周数感兴趣。 从这里得到一些帮助后，我得到了这个查询：

SELECT HerdID
      ,YEAR([Event]) As YearID
      ,DATEPART(wk,[Event]) As A
      ,MIN (DATEPART(wk,[Event])) OVER (PARTITION BY HerdID, YEAR([Event])) AS B
      ,MAX (DATEPART(wk,[Event])) OVER (PARTITION BY HerdID, YEAR([Event])) AS C
      ,COUNT([Event]) OVER (PARTITION BY HerdID, YEAR([Event])) AS D
      ,cast( ROW_NUMBER() OVER (PARTITION BY HerdID, YEAR([Event]) ORDER BY DATEPART(wk,[Event])) as dec(5,2))
        / cast (COUNT([Event]) OVER (PARTITION BY HerdID, YEAR([Event])) as dec(5,2)) AS E 

它给了我下表。

HerdID  YearID  A   B   C   D   E   
000001  2009    6   6   53  3   0.333333
000001  2009    14  6   53  3   0.666666
000001  2009    53  6   53  3   1.000000
000002  2009    5   5   34  4   0.250000
000002  2009    16  5   34  4   0.500000
000002  2009    27  5   34  4   0.750000
000002  2009    34  5   34  4   1.000000

我对每个 HerdID 有多行，我希望每年每个 herdID 有一行，在第一周的 A 列中显示累积百分比 (E) 记录为 >=50，但不是随后的周数。 所以上表将是：

HerdID  YearID  A   B   C   D   E   
000001  2009    14  6   53  3   0.666666
000002  2009    16  5   34  4   0.500000

任何帮助表示赞赏！ ☺️