| Jan | Feb | March | April | May | June | July | Aug | Sept | Oct | Nov | Dec |
1 | 16.7 | 20.8 | | | | | | | | | | |
2 | 17.6 | 18.9 | | | | | | | | | | |
3 | 18.7 | 18.9 | | | | | | | | | | |
4 | 14.6 | 18.8 | | | | | | | | | | |
5 | 13.3 | 18.5 | | | | | | | | | | |
6 | 14.5 | 15.8 | | | | | | | | | | |
7 | 16.9 | 15.8 | | | | | | | | | | |
8 | 16.4 | 15.8 | | | | | | | | | | |
9 | 15.8 | 18.2 | | | | | | | | | | |
10 | 15.6 | 20.9 | | | | | | | | | | |
11 | 15.3 | 17.8 | | | | | | | | | | |
12 | 15.0 | | | | | | | | | | | |
13 | 15.9 | | | | | | | | | | | |
14 | 15.6 | | | | | | | | | | | |
15 | 16.2 | | | | | | | | | | | |
16 | 15.8 | | | | | | | | | | | |
17 | 17.2 | | | | | | | | | | | |
18 | 16.4 | | | | | | | | | | | |
19 | 16.8 | | | | | | | | | | | |
20 | 17.1 | | | | | | | | | | | |
21 | 16.8 | | | | | | | | | | | |
22 | 16.4 | | | | | | | | | | | |
23 | 19.2 | | | | | | | | | | | |
24 | 19.2 | | | | | | | | | | | |
25 | 22.0 | | | | | | | | | | | |
26 | 22.8 | | | | | | | | | | | |
27 | 19.4 | | | | | | | | | | | |
28 | 16.8 | | | | | | | | | | | |
29 | 20.3 | | | | | | | | | | | |
30 | 20.1 | | | | | | | | | | | |
31 | 21.0 | | | | | | | | | | | |
|