Year	Years
1960	1.617
1961	2.667
1962	2.145
1963	1.902
1964	2.909
1965	2.561
1966	2.109
1967	1.479
1968	1.883
1969	2.939
1970	2.698
1971	2.551
1972	3.033
1973	3.699
1974	3.213
1975	2.369
1976	2.566
1977	2.81
1978	2.743
1979	1.978
1980	1.94
1981	1.699
1982	1.264
1983	0.8639
1984	1.137
1985	2.212
1986	2.96
1987	3.163
1988	3.615
1989	4.242
1990	4.625
1991	5.483
1992	5.409
1993	5.375
1994	5.013
1995	4.697
1996	3.922
1997	4.307
1998	4.087
1999	3.835
2000	4.174
2001	3.403
2002	3.458
2003	3.332
2004	3.374