Year	Percent
1960	1.66624
1961	1.73119
1962	1.79665
1963	1.85055
1964	1.89317
1965	1.9285
1966	1.96744
1967	2.00722
1968	2.03562
1969	2.04888
1970	2.05722
1971	2.05066
1972	2.05442
1973	2.10481
1974	2.21503
1975	2.35492
1976	2.49657
1977	2.60008
1978	2.65305
1979	2.64387
1980	2.58676
1981	2.53024
1982	2.47389
1983	2.37425
1984	2.2277
1985	2.05744
1986	1.862
1987	1.69236
1988	1.61279
1989	1.648
1990	1.75579
1991	1.88855
1992	1.97508
1993	1.9743
1994	1.8584
1995	1.66605
1996	1.46053
1997	1.28861
1998	1.14479
1999	1.04455
2000	0.9772
2001	0.91919
2002	0.86357
2003	0.82636
2004	0.81162
2005	0.81452
2006	0.82341
2007	0.84221
2008	0.8861
2009	0.95937
2010	1.0514
2011	1.15064
2012	1.24033
2013	1.30409
2014	1.3335
2015	1.336
2016	1.33272
2017	1.33051