Year	Percent
1960	2.5447
1961	1.76281
1962	1.73057
1963	1.652
1964	1.64037
1965	1.67434
1966	1.60593
1967	1.43137
1968	1.3359
1969	1.4528
1970	1.53452
1971	1.59375
1972	1.52509
1973	1.33702
1974	1.28918
1975	1.39278
1976	1.28231
1977	1.08634
1978	1.10302
1979	1.17567
1980	1.27129
1981	1.239
1982	1.08177
1983	0.99554
1984	1.00645
1985	1.06767
1986	1.14972
1987	1.2228
1988	1.22652
1989	1.1726
1990	1.25511
1991	1.72273
1992	2.03732
1993	1.93814
1994	1.80802
1995	1.66407
1996	1.59627
1997	1.61273
1998	1.68143
1999	1.6967
2000	1.71592
2001	2.09358
2002	2.27331
2003	2.0121
2004	1.79694
2005	1.59347
2006	1.37074
2007	1.29141
2008	1.40495
2009	1.54639
2010	1.48858
2011	1.31781
2012	1.17361
2013	0.96871
2014	0.92223
2015	0.9803
2016	1.04322
2017	1.08678