月份 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
发生次数(次) |
0.4 |
1.2 |
3.4 |
4.5 |
3.1 |
0.1 |
0.1 |
0.1 |
0 |
0.3 |
0.6 |
0.4 |