Year,F
1973,0.89
1974,1.08
1975,0.67
1976,0.51
1977,0.88
1978,0.93
1979,0.91
1980,1.21
1981,1.78
1982,1.06
1983,1.05
1984,1.64
1985,1.69
1986,1.47
1987,1.83
1988,2.61
1989,1.62
1990,1.93
1991,2.96
1992,2.63
1993,0.86
1994,2.32
1995,1.08
1996,1.59
1997,1.54
1998,1.38
1999,2.12
2000,0.88
2001,1.83
2002,0.99
2003,0.55
2004,0.99