Year,Spring_kg_tow,Fall_kg_tow
1963,,0.982
1964,,0.092
1965,,0.502
1966,,1.159
1967,,0.354
1968,3.236,0.115
1969,2.083,0.063
1970,0.615,0.046
1971,0.169,0.32
1972,0.219,0.058
1973,1.263,0.006
1974,0.767,0.018
1975,0.322,0.061
1976,0.216,0.024
1977,0.226,0.005
1978,0.399,0.09
1979,0.419,0.003
1980,0.7,0.001
1981,0.358,0.001
1982,0.037,0.021
1983,0.055,0.033
1984,0.134,0.234
1985,0.299,0.411
1986,2.479,0.158
1987,1.012,1.577
1988,1.995,2.249
1989,1.318,2.514
1990,0.917,1.635
1991,2.292,2.954
1992,2.755,9.249
1993,7.683,2.513
1994,3.881,2.154
1995,3.143,13.122
1996,3.809,4.644
1997,4.084,4.867
1998,4.726,2.844
1999,9.447,1.836
2000,2.803,3.178
2001,3.221,3.689
2002,2.628,10.744
2003,1.869,6.234
2004,2.223,5.038
2005,1.487,3.371
2006,2.893,