Year	Years
1960	1.628
1961	1.009
1962	1.19
1963	1.248
1964	2.034
1965	2
1966	2.47
1967	2.598
1968	3.292
1969	3.126
1970	2.952
1971	3.149
1972	3.146
1973	3.309
1974	2.689
1975	2.05
1976	2.027
1977	2.295
1978	2.322
1979	2.283
1980	2.206
1981	2.095
1982	1.375
1983	1.292
1984	2.088
1985	2.513
1986	2.287
1987	2.137
1988	1.991
1989	2.039
1990	2.284
1991	1.994
1992	2.497
1993	2.298
1994	1.994
1995	1.835
1996	1.88
1997	2.022
1998	2.06
1999	2.17
2000	2.375
2001	2.461
2002	2.256
2003	2.241
2004	2.268