Year	Years
1960	4.092
1961	3.873
1962	3.622
1963	4.225
1964	3.876
1965	3.701
1966	3.698
1967	3.922
1968	4.247
1969	4.522
1970	4.4
1971	3.85
1972	4.256
1973	4.551
1974	4.577
1975	3.967
1976	3.566
1977	3.625
1978	3.508
1979	3.158
1980	2.933
1981	2.974
1982	2.664
1983	2.277
1984	1.989
1985	2.176
1986	2.535
1987	2.652
1988	3.117
1989	3.099
1990	2.351
1991	1.277
1992	0.4952
1993	0.01983
1994	0.1729
1995	0.4759
1996	0.5229
1997	0.8926
1998	0.9568
1999	0.6196
2000	1.352
2001	2.32
2002	3.084
2003	3.541
2004	3.496