表格“测试”：
+---------+------+-------+
| Section | Test | Count |
+---------+------+-------+
| A | T1 | 20 |
| A | T2 | 10 |
| A | T3 | 15 |
| A | T4 | 30 |
| B | T1 | 10 |
| B | T2 | 40 |
| B | T3 | 25 |
| B | T4 | 30 |
+---------+------+-------+
我想按部分计算每个测试组的计数百分比（例如：第一次计算：（20 * 100）/（20 + 10 + 15 + 30））。结果表应如下所示。
+---------+------+-------+------------+
| Section | Test | Count | Percentage |
+---------+------+-------+------------+
| A | T1 | 20 | 26.6 |
| A | T2 | 10 | 13.3 |
| A | T3 | 15 | 20 |
| A | T4 | 30 | 40 |
| B | T1 | 10 | 9.5 |
| B | T2 | 40 | 38.1 |
| B | T3 | 25 | 23.8 |
| B | T4 | 30 | 28.6 |
+---------+------+-------+------------+
请让我知道任何好的解决方案。