Year	Percent
1960	1.76904
1961	1.83618
1962	2.51318
1963	1.92714
1964	1.85927
1965	1.79734
1966	1.71395
1967	1.61552
1968	1.75507
1969	1.43748
1970	1.37585
1971	1.44905
1972	1.53085
1973	1.4537
1974	1.27018
1975	1.50816
1976	1.34012
1977	1.40535
1978	1.42944
1979	1.47901
1980	1.67094
1981	1.54559
1982	1.64375
1983	1.82326
1984	1.60404
1985	1.67658
1986	1.72391
1987	1.64553
1988	1.60769
1989	1.53431
1990	1.56335
1991	1.78123
1992	1.90713
1993	1.86801
1994	1.7556
1995	1.42254
1996	1.53047
1997	1.53516
1998	1.46318
1999	1.2231
2000	1.24115
2001	1.14451
2002	1.15464
2003	1.44686
2004	1.47016
2005	1.46719
2006	1.44477
2007	1.29089
2008	1.39492
2009	1.56693
2010	1.50007
2011	1.49795
2012	1.53609
2013	1.54128
2014	1.46199
2015	1.46244
2016	1.43218
2017	1.43776