| Jan | Feb | March | April | May | June | July | Aug | Sept | Oct | Nov | Dec |
| 1 | 17.2 | 29.4 | 14.2 | 24.4 | | | | | | | | | | | | | | | | | | | | |
| 2 | 16.6 | 27.7 | 17.6 | 32.5 | | | | | | | | | | | | | | | | | | | | |
| 3 | 14.4 | 19.5 | 18.5 | 29.7 | | | | | | | | | | | | | | | | | | | | |
| 4 | 13.3 | 20.9 | 15.9 | 20.0 | | | | | | | | | | | | | | | | | | | | |
| 5 | 10.0 | 24.5 | 12.9 | 22.4 | | | | | | | | | | | | | | | | | | | | |
| 6 | 14.3 | 28.0 | 12.0 | 26.2 | | | | | | | | | | | | | | | | | | | | |
| 7 | 17.2 | 28.6 | 13.0 | 29.5 | | | | | | | | | | | | | | | | | | | | |
| 8 | 16.8 | 24.4 | 15.5 | 28.2 | | | | | | | | | | | | | | | | | | | | |
| 9 | 15.9 | 32.6 | 16.5 | 26.3 | | | | | | | | | | | | | | | | | | | | |
| 10 | 16.9 | 32.3 | 17.7 | 28.0 | | | | | | | | | | | | | | | | | | | | |
| 11 | 20.2 | 36.4 | 16.9 | 25.3 | | | | | | | | | | | | | | | | | | | | |
| 12 | 18.0 | 28.0 | 17.1 | 26.4 | | | | | | | | | | | | | | | | | | | | |
| 13 | 16.2 | 28.8 | 20.3 | 30.5 | | | | | | | | | | | | | | | | | | | | |
| 14 | 18.6 | 28.8 | 16.9 | 21.4 | | | | | | | | | | | | | | | | | | | | |
| 15 | 17.9 | 24.2 | 12.9 | 17.0 | | | | | | | | | | | | | | | | | | | | |
| 16 | 17.7 | 30.9 | 10.2 | 24.5 | | | | | | | | | | | | | | | | | | | | |
| 17 | 14.4 | 19.5 | | | | | | | | | | | | | | | | | | | | | | |
| 18 | 13.6 | 16.2 | | | | | | | | | | | | | | | | | | | | | | |
| 19 | 15.6 | 19.5 | | | | | | | | | | | | | | | | | | | | | | |
| 20 | 14.9 | 20.0 | | | | | | | | | | | | | | | | | | | | | | |
| 21 | 15.0 | 17.0 | | | | | | | | | | | | | | | | | | | | | | |
| 22 | 16.1 | 30.7 | | | | | | | | | | | | | | | | | | | | | | |
| 23 | 16.0 | 29.1 | | | | | | | | | | | | | | | | | | | | | | |
| 24 | 16.3 | 23.3 | | | | | | | | | | | | | | | | | | | | | | |
| 25 | 17.8 | 25.7 | | | | | | | | | | | | | | | | | | | | | | |
| 26 | 16.1 | 25.4 | | | | | | | | | | | | | | | | | | | | | | |
| 27 | 12.2 | 24.8 | | | | | | | | | | | | | | | | | | | | | | |
| 28 | 16.8 | 24.8 | | | | | | | | | | | | | | | | | | | | | | |
| 29 | 14.5 | 31.5 | | | | | | | | | | | | | | | | | | | | | |
| 30 | 17.2 | 24.7 | | | | | | | | | | | | | | | | | | | | | |
| 31 | 14.7 | 30.6 | | | | | | | | | | | | | | | | | |
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