Year	Percent
1960	2.40546
1961	2.48404
1962	2.5502
1963	2.59444
1964	2.61193
1965	2.6133
1966	2.60659
1967	2.60544
1968	2.61285
1969	2.6312
1970	2.65855
1971	2.6857
1972	2.70868
1973	2.72659
1974	2.73837
1975	2.74687
1976	2.74422
1977	2.74331
1978	2.76046
1979	2.80122
1980	2.85072
1981	2.86059
1982	2.84159
1983	2.84523
1984	2.87838
1985	2.90625
1986	3.00402
1987	3.02856
1988	2.76585
1989	2.15239
1990	1.34325
1991	0.44823
1992	-0.27906
1993	-0.62838
1994	-0.43994
1995	0.15273
1996	0.84492
1997	1.43274
1998	1.96928
1999	2.3916
2000	2.70478
2001	3.02851
2002	3.30511
2003	3.36296
2004	3.16888
2005	2.82056
2006	2.43031
2007	2.10918
2008	1.89141
2009	1.81904
2010	1.85052
2011	1.89165