| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
| 1901 | 24.0 | 22.0 | 27.0 | 34.0 | 47.0 | 56.0 | 67.0 | 66.0 | 47.0 | 38.0 | 28.0 | 15.0 | 15.0 |
| 1902 | 22.0 | 25.0 | 33.0 | 45.0 | 56.0 | 55.0 | 66.0 | 69.0 | 45.0 | 42.0 | 31.0 | 25.0 | 22.0 |
| 1903 | 23.0 | 13.0 | 34.0 | 35.0 | 40.0 | 48.0 | 62.0 | 67.0 | 45.0 | 35.0 | 17.0 | 22.0 | 13.0 |
| 1904 | 15.0 | 23.0 | 31.0 | 34.0 | 46.0 | 60.0 | 66.0 | 61.0 | 61.0 | 37.0 | 23.0 | 21.0 | 15.0 |
| 1905 | 17.0 | 8.0 | 42.0 | 41.0 | 56.0 | 66.0 | 59.0 | 64.0 | 55.0 | 36.0 | 29.0 | 23.0 | 8.0 |
| 1906 | 19.0 | 20.0 | 27.0 | 39.0 | 45.0 | 61.0 | 62.0 | 56.0 | 61.0 | 34.0 | 27.0 | 27.0 | 19.0 |
| 1907 | 27.0 | 35.0 | 38.0 | 45.0 | 53.0 | 57.0 | 67.0 | 52.0 | 37.0 | 21.0 | 27.0 | 21.0 | |
| 1908 | 22.0 | 22.0 | 38.0 | 37.0 | 40.0 | 61.0 | 63.0 | 65.0 | 43.0 | 32.0 | 24.0 | 25.0 | 22.0 |
| 1909 | 18.0 | 20.0 | 31.0 | 35.0 | 39.0 | 61.0 | 69.0 | 68.0 | 37.0 | 37.0 | 30.0 | 19.0 | 18.0 |
| 1910 | 16.0 | 13.0 | 36.0 | 34.0 | 50.0 | 55.0 | 63.0 | 68.0 | 51.0 | 25.0 | 28.0 | 13.0 | |
| 1911 | 10.0 | 22.0 | 36.0 | 46.0 | 47.0 | 60.0 | 64.0 | 56.0 | 59.0 | 35.0 | 16.0 | 22.0 | 10.0 |
| 1912 | 11.0 | 15.0 | 30.0 | 37.0 | 46.0 | 54.0 | 70.0 | 65.0 | 50.0 | 42.0 | 21.0 | 25.0 | 11.0 |
| 1913 | 16.0 | 25.0 | 27.0 | 37.0 | 53.0 | 54.0 | 67.0 | 58.0 | 40.0 | 33.0 | 31.0 | 23.0 | 16.0 |
| 1914 | 26.0 | 18.0 | 28.0 | 34.0 | 52.0 | 62.0 | 68.0 | 67.0 | 50.0 | 28.0 | 25.0 | 20.0 | 18.0 |
| 1915 | 23.0 | 27.0 | 21.0 | 28.0 | 48.0 | 61.0 | 60.0 | 59.0 | 56.0 | 42.0 | 25.0 | 22.0 | 21.0 |
| 1916 | 15.0 | 21.0 | 28.0 | 33.0 | 49.0 | 57.0 | 70.0 | 59.0 | 40.0 | 34.0 | 20.0 | 16.0 | 15.0 |
| 1917 | 24.0 | 15.0 | 24.0 | 38.0 | 41.0 | 51.0 | 64.0 | 56.0 | 49.0 | 26.0 | 27.0 | 11.0 | 11.0 |
| 1918 | 2.0 | 24.0 | 32.0 | 37.0 | 51.0 | 67.0 | 63.0 | 65.0 | 43.0 | 35.0 | 29.0 | 19.0 | 2.0 |
| 1919 | 16.0 | 27.0 | 28.0 | 37.0 | 46.0 | 50.0 | 66.0 | 65.0 | 53.0 | 50.0 | 27.0 | 11.0 | 11.0 |
| 1920 | 27.0 | 23.0 | 28.0 | 55.0 | 58.0 | 65.0 | 61.0 | 46.0 | 33.0 | 24.0 | 21.0 | 21.0 | |
| 1921 | 26.0 | 27.0 | 34.0 | 34.0 | 45.0 | 63.0 | 67.0 | 63.0 | 64.0 | 36.0 | 31.0 | 21.0 | 21.0 |
| 1922 | 26.0 | 24.0 | 23.0 | 41.0 | 53. | 62.0 | 57.0 | 60.0 | 55.0 | 35.0 | 29.0 | 26.0 | 23.0 |
| 1923 | 27.0 | 22.0 | 18.0 | 37.0 | 46.0 | 60.0 | 61.0 | 56.0 | 53.0 | 31.0 | 27.0 | 25.0 | 18.0 |
| 1924 | 12.0 | 16.0 | 25.0 | 31.0 | 43.0 | 57.0 | 53.0 | 63.0 | 48.0 | 35.0 | 25.0 | 15.0 | 12.0 |
| 1925 | 20.0 | 24.0 | 31.0 | 46.0 | 38.0 | 65.0 | 69.0 | 63.0 | 62.0 | 34.0 | 28.0 | 18.0 | 18.0 |
| 1926 | 25.0 | 30.0 | 30.0 | 36.0 | 45.0 | 54.0 | 62.0 | 66.0 | 54.0 | 39.0 | 27.0 | 22.0 | 22.0 |
| 1927 | 20.0 | 29.0 | 30.0 | 40.0 | 53.0 | 62.0 | 64.0 | 57.0 | 50.0 | 40.0 | 30.0 | 19.0 | 19.0 |
| 1928 | 10.0 | 28.0 | 34.0 | 31.0 | 45.0 | 56.0 | 68.0 | 68.0 | 48.0 | 37.0 | 27.0 | 21.0 | 10.0 |
| 1929 | 18.0 | 18.0 | 27.0 | 44.0 | 40.0 | 60.0 | 65.0 | 60.0 | 55.0 | 31.0 | 21.0 | 1.0 | 1.0 |
| 1930 | -4.0 | 28.0 | 25.0 | 46.0 | 52.0 | 49.0 | 66.0 | 61.0 | 52.0 | 34.0 | 25.0 | 24.0 | -4.0 |