Year	Percent
1960	3.1568
1961	2.76259
1962	2.73119
1963	2.7009
1964	2.66959
1965	2.63327
1966	2.06175
1967	2.03213
1968	2.0027
1969	1.96608
1970	1.91147
1971	1.85778
1972	1.82958
1973	1.80138
1974	1.77329
1975	1.74748
1976	1.85122
1977	1.8215
1978	1.79768
1979	1.58275
1980	1.35113
1981	1.29919
1982	1.25034
1983	1.21224
1984	1.362
1985	1.37075
1986	1.30398
1987	1.27488
1988	1.21838
1989	0.88269
1990	0.38034
1991	0.21682
1992	0.03828
1993	-0.11918
1994	-0.13078
1995	0.02133
1996	-0.15228
1997	-0.17077
1998	-0.17096
1999	-0.31629
2000	-0.42602
2001	-0.4296
2002	-0.46688
2003	-0.4101
2004	-0.3413
2005	-0.3202
2006	-0.26608
2007	-0.10983
2008	0.01722
2009	0.08988
2010	0.10597
2011	0.13902
2012	0.24829
2013	0.31045
2014	0.33542
2015	0.32769
2016	0.32408
2017	0.27814