Year	Years
1960	2.302
1961	2.028
1962	2.139
1963	1.992
1964	2.114
1965	1.995
1966	2.041
1967	2.14
1968	2.462
1969	2.33
1970	2.159
1971	2.262
1972	2.485
1973	2.895
1974	2.369
1975	2.092
1976	2.281
1977	2.145
1978	2.168
1979	2.301
1980	1.898
1981	1.548
1982	1.382
1983	1.02
1984	1.347
1985	1.753
1986	1.824
1987	2.185
1988	2.37
1989	2.303
1990	2.532
1991	2.46
1992	2.332
1993	2.197
1994	2.37
1995	2.285
1996	2.151
1997	2.018
1998	1.809
1999	1.866
2000	2.188
2001	2.557
2002	2.706
2003	2.696
2004	2.571