Year,Spring_kg_tow,Fall_kg_tow
1962,,
1963,,5.870
1964,,2.840
1965,,3.800
1966,,4.900
1967,,2.690
1968,3.400,2.910
1969,2.680,2.360
1970,1.810,2.010
1971,1.260,1.960
1972,1.320,1.600
1973,1.850,1.940
1974,1.940,1.420
1975,1.720,2.430
1976,3.370,2.990
1977,5.110,3.520
1978,3.820,4.660
1979,3.620,4.000
1980,4.780,5.120
1981,5.880,5.620
1982,3.800,2.490
1983,4.600,3.450
1984,1.420,2.020
1985,1.880,2.000
1986,0.920,1.560
1987,0.810,1.090
1988,0.840,1.460
1989,0.750,1.170
1990,0.750,2.900
1991,1.050,1.560
1992,1.360,1.780
1993,1.390,2.390
1994,0.850,2.670
1995,1.940,2.580
1996,1.690,2.230
1997,1.620,1.940
1998,1.110,2.220
1999,1.200,2.570
2000,2.300,2.790
2001,2.190,2.630
2002,1.760,2.241
2003,0.868,2.269
2004,1.353,0.964
2005,0.830,0.990
2006,,