Year	Years
1963	1.416
1964	1.981
1965	1.735
1966	2.586
1967	2.49
1968	3.343
1969	4.639
1970	5.435
1971	5.851
1972	6.23
1973	6.506
1974	6.715
1975	6.762
1976	6.655
1977	7.209
1978	7.29
1979	6.827
1980	5.685
1981	5.418
1982	5.723
1983	5.711
1984	5.771
1985	6.001
1986	6.02
1987	6.156
1988	6.172
1989	6.142
1990	7.727
1991	8.204
1992	7.999
1993	7.641
1994	7.665
1995	7.918
1996	7.669
1997	6.967
1998	5.002
1999	5.305
2000	5.053
2001	4.51
2002	4.714
2003	4.44
2004	4.103