Year,Spring_kg_tow,Fall_kg_tow
1963,,
1964,,
1965,,
1966,,
1967,,1.250
1968,0.160,1.000
1969,0.160,0.610
1970,0.090,0.130
1971,0.280,0.270
1972,0.210,0.270
1973,0.540,0.630
1974,1.260,1.860
1975,1.610,2.480
1976,2.000,0.850
1977,1.740,1.750
1978,1.400,0.400
1979,0.350,0.940
1980,0.780,0.570
1981,0.800,0.720
1982,1.110,0.900
1983,0.530,0.470
1984,0.380,0.650
1985,1.200,0.870
1986,0.820,0.450
1987,0.380,0.280
1988,0.680,0.110
1989,0.240,0.080
1990,0.270,0.190
1991,0.350,0.170
1992,0.460,0.490
1993,0.480,0.040
1994,0.460,0.350
1995,0.460,0.830
1996,0.670,0.450
1997,0.610,0.920
1998,0.760,1.580
1999,1.010,1.660
2000,1.700,1.820
2001,2.160,1.550
2002,2.290,1.400
2003,2.420,1.930
2004,2.430,3.060
2005,1.590,1.830
2006,1.340,1.793