Year,Spring_kg_tow,Fall_kg_tow 1963,, 1964,, 1965,, 1966,, 1967,, 1968,, 1969,, 1970,, 1971,, 1972,, 1973,, 1974,, 1975,, 1976,, 1977,, 1978,18.3727,11.7496 1979,14.407,28.9783 1980,17.4941,15.9398 1981,28.3704,13.2277 1982,14.6871,23.635 1983,27.2334,15.7715 1984,15.9767,10.8172 1985,13.5938,7.53673 1986,14.724,6.81975 1987,17.6478,7.73743 1988,10.6165,7.25382 1989,13.3172,7.46157 1990,12.9657,13.4516 1991,11.5867,16.1755 1992,13.9382,13.4714 1993,12.3902,14.9956 1994,10.0356,13.5604 1995,14.5599,17.2753 1996,12.8227,13.0313 1997,14.7957,15.0823 1998,15.7562,14.9343 1999,14.1978,23.0774 2000,35.453,25.6933 2001,23.8909,18.3666 2002,21.4044,18.4006 2003,17.7175,16.8025 2004,12.2151,16.1937 2005,13.7441,12.415