Year,Spring_kg_tow,Fall_kg_tow
1963,,50.697
1964,,18.829
1965,,17.644
1966,,13.859
1967,,16.853
1968,7.887,17.241
1969,7.376,12.854
1970,1.725,7.354
1971,2.523,8.137
1972,0.867,3.036
1973,1.597,8.583
1974,1.059,3.347
1975,3.482,6.807
1976,6.350,8.040
1977,6.725,8.752
1978,1.434,21.658
1979,3.948,15.567
1980,2.672,9.835
1981,3.545,10.874
1982,2.555,4.164
1983,3.567,5.219
1984,1.144,3.893
1985,1.882,6.149
1986,1.284,1.392
1987,0.062,2.645
1988,0.301,1.476
1989,0.124,0.631
1990,0.000,0.432
1991,0.066,0.120
1992,0.271,0.091
1993,0.200,0.472
1994,0.253,0.217
1995,0.350,1.099
1996,0.338,3.543
1997,1.222,2.424
1998,0.112,2.917
1999,1.108,4.910
2000,1.815,14.032
2001,3.215,11.983
2002,2.794,4.839
2003,3.909,5.361
2004,1.200,7.168
2005,0.968,3.932