Year	Percent
1960	2.25075
1961	2.03124
1962	2.26775
1963	1.96963
1964	1.93056
1965	1.88487
1966	2.07962
1967	1.85196
1968	2.29767
1969	2.43417
1970	2.28662
1971	2.10797
1972	2.31778
1973	2.11074
1974	2.20756
1975	2.00426
1976	2.32105
1977	2.31423
1978	2.35796
1979	2.49706
1980	2.4899
1981	2.58211
1982	2.66031
1983	2.93627
1984	2.96601
1985	2.95472
1986	2.62504
1987	2.6147
1988	2.48938
1989	2.35968
1990	2.29331
1991	2.12919
1992	2.0428
1993	2.01187
1994	2.00134
1995	1.91702
1996	1.81444
1997	1.72282
1998	1.75732
1999	1.75523
2000	1.72552
2001	1.633
2002	1.45649
2003	1.42041
2004	1.42693
2005	1.38239
2006	1.36437
2007	1.35646
2008	1.35943
2009	1.34611
2010	1.37682
2011	1.32356
2012	1.4117
2013	1.26614
2014	1.24762
2015	1.26799
2016	1.13297
2017	1.24256