Annual Data Summary
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| 1 | 7.5 | 4.6 | 8.9 | 10.2 | 18.1 | | | | | | | |
| 2 | 6.7 | 5.1 | 9.2 | 10.6 | 15.3 | | | | | | | |
| 3 | 7.5 | 8.1 | 9.3 | 6.7 | 12.1 | | | | | | | |
| 4 | 8.7 | 8.3 | 7.7 | 9.0 | 8.6 | | | | | | | |
| 5 | 8.2 | 8.4 | 9.2 | 10.7 | 8.6 | | | | | | | |
| 6 | 9.8 | 9.2 | 10.1 | 11.1 | 8.9 | | | | | | | |
| 7 | 9.8 | 7.6 | 7.7 | 10.9 | 10.7 | | | | | | | |
| 8 | 10.2 | 8.9 | 10.2 | 10.9 | 11.0 | | | | | | | |
| 9 | 9.2 | 8.9 | 10.3 | 9.4 | 11.4 | | | | | | | |
| 10 | 9.4 | 9.1 | 9.4 | 10.2 | 9.6 | | | | | | | |
| 11 | 10.4 | 8.0 | 10.7 | 11.2 | 10.7 | | | | | | | |
| 12 | 8.2 | 8.5 | 9.4 | 10.2 | 12.2 | | | | | | | |
| 13 | 8.1 | 9.1 | 10.0 | 10.3 | 10.2 | | | | | | | |
| 14 | 7.2 | 9.5 | 9.8 | 8.4 | 11.0 | | | | | | | |
| 15 | 6.7 | 9.4 | 10.7 | 8.5 | 9.4 | | | | | | | |
| 16 | 8.2 | 9.6 | 9.9 | 9.8 | 8.4 | | | | | | | |
| 17 | 10.2 | 9.2 | 9.2 | 10.7 | | | | | | | | |
| 18 | 7.8 | 5.7 | 9.2 | 11.9 | | | | | | | | |
| 19 | 7.1 | 9.3 | 10.2 | 11.7 | | | | | | | | |
| 20 | 9.4 | 9.8 | 10.8 | 10.9 | | | | | | | | |
| 21 | 8.7 | 9.6 | 11.6 | 12.5 | | | | | | | | |
| 22 | 7.8 | 10.1 | 11.5 | 12.1 | | | | | | | | |
| 23 | 7.7 | 11.3 | 12.5 | 12.4 | | | | | | | | |
| 24 | 9.5 | 9.2 | 13.4 | 11.2 | | | | | | | | |
| 25 | 9.3 | 9.5 | 13.8 | 9.7 | | | | | | | | |
| 26 | 6.3 | 9.7 | 14.5 | 9.4 | | | | | | | | |
| 27 | 7.0 | 10.2 | 14.3 | 9.1 | | | | | | | | |
| 28 | 7.4 | 10.1 | 10.7 | 10.9 | | | | | | | | |
| 29 | 6.7 | 10.4 | 9.7 | 10.5 | | | | | | | | |
| 30 | 4.9 | | 10.7 | 13.8 | | | | | | | | |
| 31 | 4.4 | | 10.6 | | | | | | | | | |