Year	Years
1960	2.43
1961	1.832
1962	2.273
1963	2.86
1964	3.08
1965	3.028
1966	3.131
1967	3.32
1968	3.779
1969	4.406
1970	4.266
1971	3.87
1972	3.203
1973	3.029
1974	3.243
1975	3.043
1976	2.412
1977	2.174
1978	1.303
1979	1.079
1980	0.7129
1981	0.711
1982	0.5585
1983	-1.181
1984	-1.648
1985	-1.808
1986	-0.9424
1987	-0.157
1988	-0.6376
1989	-2.324
1990	-3.383
1991	-3.575
1992	-3.709
1993	-2.108
1994	-1.247
1995	-0.6886
1996	-1.435
1997	-1.653
1998	-0.7596
1999	0.9553
2000	1.785
2001	1.677
2002	2.242
2003	2.219