Year	Years
1960	2.642
1961	2.966
1962	3.145
1963	3.296
1964	3.34
1965	3.427
1966	3.312
1967	3.407
1968	3.434
1969	3.364
1970	3.655
1971	3.174
1972	3.02
1973	2.816
1974	2.593
1975	2.57
1976	2.58
1977	2.112
1978	1.891
1979	1.862
1980	1.482
1981	1.363
1982	1.256
1983	1.074
1984	1.178
1985	1.164
1986	1.263
1987	1.811
1988	1.993
1989	1.896
1990	1.796
1991	1.695
1992	1.423
1993	1.015
1994	0.9538
1995	1.034
1996	0.8834
1997	0.7587
1998	0.8972
1999	1.105
2000	1.513
2001	1.803
2002	2.124
2003	2.597
2004	2.612