| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
1 | 16.5 | 12.9 | 9.5 | | | | | | | | | |
2 | 16.2 | 13.2 | 15.1 | | | | | | | | | |
3 | 17.1 | 13.6 | 16.7 | | | | | | | | | |
4 | 17.7 | 14.5 | 15.6 | | | | | | | | | |
5 | 17.2 | 13.6 | 15.9 | | | | | | | | | |
6 | 16.7 | 11.2 | 14.8 | | | | | | | | | |
7 | 12.1 | 10.9 | 14.7 | | | | | | | | | |
8 | 13.6 | 9.3 | 15.2 | | | | | | | | | |
9 | 15.8 | 7.4 | 16.8 | | | | | | | | | |
10 | 16.9 | 11.0 | 18.1 | | | | | | | | | |
11 | 9.6 | 14.8 | 18.3 | | | | | | | | | |
12 | 14.3 | 13.7 | 19.0 | | | | | | | | | |
13 | 13.3 | 14.5 | 17.4 | | | | | | | | | |
14 | 14.3 | 15.6 | 16.7 | | | | | | | | | |
15 | 12.7 | 13.9 | 18.2 | | | | | | | | | |
16 | 12.8 | 12.9 | 15.6 | | | | | | | | | |
17 | 11.7 | 14.7 | 17.2 | | | | | | | | | |
18 | 12.7 | 13.7 | 16.8 | | | | | | | | | |
19 | 9.8 | 16.2 | 14.1 | | | | | | | | | |
20 | 9.3 | 17.2 | 18.7 | | | | | | | | | |
21 | 8.6 | 13.5 | 18.7 | | | | | | | | | |
22 | 10.3 | 14.0 | 19.1 | | | | | | | | | |
23 | 9.3 | 16.0 | 19.1 | | | | | | | | | |
24 | 14.0 | 13.7 | 18.6 | | | | | | | | | |
25 | 12.7 | 13.3 | 18.3 | | | | | | | | | |
26 | 12.2 | 12.3 | 16.6 | | | | | | | | | |
27 | 9.0 | 10.4 | 20.1 | | | | | | | | | |
28 | 8.8 | 12.6 | 16.8 | | | | | | | | | |
29 | 12.2 | | 15.9 | | | | | | | | | |
30 | 10.8 | | | | | | | | | | | |
31 | 15.6 | | | | | | | | | | | |