| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
| 1901 | 1.83 | 5.11 | 3.51 | 5.79 | 2.25 | 5.41 | 4.62 | 2.18 | 5.17 | 4.50 | 2.59 | 2.19 | 45.15 |
| 1902 | 2.51 | 3.60 | 5.21 | 2.91 | 4.53 | 14.22 | 5.77 | 0.4 8 | 9.99 | 5.57 | 6.19 | 2.04 | 63.02 |
| 1903 | 4.86 | 6.70 | 5.05 | 1.23 | 2.98 | 2.99 | 7.52 | 3.01 | 0.15 | 5.98 | 0.37 | 5.17 | 46.01 |
| 1904 | 1.86 | 3.86 | 3.23 | 4.41 | 2.71 | 4.06 | 5.54 | 3.56 | 4.68 | 0.33 | 0.88 | 8.03 | 43.15 |
| 1905 | 3.19 | 3.98 | 5.62 | 8.88 | 8.99 | 5.21 | 9.43 | 3.69 | 2.74 | 1.78 | 10.16 | 5.86 | 69.53 |
| 1906 | 4.85 | 1.73 | 1.63 | 4.26 | 1.54 | 4.65 | 7.91 | 1.68 | 1.74 | 4.12 | 1.91 | 3.60 | 39.62 |
| 1907 | 2.96 | 2.84 | 2.15 | 4.56 | 9.07 | 0.21 | 2.33 | 0.15 | 0.63 | 6.44 | 10.39 | 4.55 | 46.28 |
| 1908 | 2.31 | 6.37 | 3.40 | 4.12 | 2.87 | 0.92 | 2.46 | 3.92 | 5.59 | 0.12 | 2.98 | 1.56 | 36.62 |
| 1909 | 0.44 | 3.24 | 2.01 | 3.93 | 4.79 | 3.90 | 4.33 | 1.15 | 1.23 | 2.89 | 0.85 | 8.40 | 37.16 |
| 1910 | 1.56 | 9.76 | 0.89 | 4.22 | 8.52 | 4.92 | 2.14 | 1.84 | 0.94 | 2.27 | 3.41 | 40.41 | |
| 1911 | 0.00 | 2.93 | 3.89 | 9.62 | 0.61 | 0.52 | 11.17 | 2.09 | 0.53 | 1.84 | 5.00 | 10.51 | 48.71 |
| 1912 | 1.96 | 3.57 | 7.18 | 7.46 | 9.44 | 4.66 | 0.64 | 2.30 | 0.00 | 0.91 | 0.80 | 6.49 | 45.41 |
| 1913 | 4.04 | 3.98 | 4.63 | 4.42 | 5.01 | 1.61 | 1.59 | 1.45 | 12.39 | 4.46 | 2.94 | 6.14 | 52.66 |
| 1914 | 1.22 | 5.03 | 4.24 | 4.08 | 8.89 | 1.25 | 0.26 | 5.22 | 1.83 | 0.67 | 4.11 | 8.90 | 45.77 |
| 1915 | 4.61 | 3.19 | 2.30 | 2.82 | 2.87 | 0.75 | 4.61 | 7.85 | 1.53 | 1.21 | 3.03 | 2.44 | 37.21 |
1916 |
7.66 |
0.58 |
0.81 |
5.28 |
10.74 |
2.43 |
3.57 |
0.76 |
0.67 |
1.27 |
3.75 |
3.18 |
40.71 |
1917 |
3.79 |
4.26 |
1.91 |
3.27 |
3.25 |
0.77 |
5.83 |
0.06 |
3.74 |
1.38 |
0.69 |
0.11 |
29.06 |
1918 |
1.45 |
0.92 |
1.81 |
6.99 |
1.67 |
2.63 |
2.28 |
3.31 |
3.87 |
4.50 |
6.55 |
3.02 |
39.00 |
1919 |
4.16 |
4.49 |
2.48 |
1.29 |
6.96 |
8.72 |
1.82 |
5.49 |
2.42 |
9.65 |
4.06 |
1.50 |
53.04 |
1920 |
6.93 |
1.17 |
5.33 |
4.94 |
4.57 |
3.06 |
4.74 |
6.83 |
1.47 |
3.51 |
4.66 |
5.69 |
52.90 |
1921 |
3.12 |
2.16 |
7.28 |
6.30 |
1.71 |
5.90 |
7.10 |
3.21 |
3.22 |
1.05 |
0.61 |
4.20 |
45.86 |
| 1922 | 6.36 | 6.10 | 8.35 | 11.66 | 5.05 | 2.74 | 3.11 | 3.41 | 1.03 | 0.70 | 5.26 | 3.88 | 57.65 |
| 1923 | 3.75 | 6.20 | 6.22 | 9.90 | 4.92 | 4.20 | 1.42 | 1.84 | 8.80 | 2.71 | 5.07 | 9.38 | 64.41 |
| 1924 | 5.01 | 5.16 | 4.35 | 5.71 | 9.46 | 3.07 | 0.06 | 0.00 | 1.97 | 0.05 | 2.14 | 2.75 | 39.73 |
| 1925 | 5.77 | 1.44 | 1.00 | 1.10 | 1.85 | 0.28 | 3.02 | 0.63 | 2.63 | 11.14 | 8.79 | 0.93 | 38.58 |
| 1926 | 3.65 | 0.60 | 8.39 | 4.95 | 2.40 | 6.62 | 7.35 | 1.76 | 0.50 | 0.68 | 3.50 | 7.61 | 48.01 |
| 1927 | 1.27 | 2.25 | 7.10 | 6.13 | 3.54 | 7.47 | 0.89 | 0.56 | 2.49 | 3.65 | 1.22 | 4.42 | 40.99 |
| 1928 | 0.82 | 3.38 | 5.66 | 2.46 | 2.92 | 4.38 | 5.15 | 0.94 | 1.08 | 2.31 | 5.53 | 3.03 | 37.66 |
| 1929 | 3.76 | 2.63 | 3.00 | 4.67 | 12.73 | 3.28 | 3.98 | 0.89 | 1.47 | 1.55 | 7.69 | 7.39 | 53.04 |
| 1930 | 6.45 | 4.46 | 2.35 | 0.48 | 6.66 | 2.36 | 1.74 | 2.45 | 4.57 | 5.48 | 5.53 | 3.17 | 45.70 |