| Season | Number | Average | Percentage % | Standard deviation |
| Autumn | 83 | 2.7 | 15.1 | 2.1 |
| Winter | 120 | 3.9 | 21.9 | 3.4 |
| Spring | 297 | 9.5 | 54.1 | 7.1 |
| Summer | 49 | 1.6 | 8.9 | 4.1 |