Year	Percent
1960	1.77846
1961	1.70291
1962	1.80882
1963	1.85586
1964	1.70494
1965	1.5492
1966	1.65173
1967	1.73994
1968	1.86747
1969	2.09089
1970	2.15676
1971	2.06999
1972	2.33616
1973	2.8138
1974	3.55804
1976	3.93134
1977	3.62131
1978	2.58177
1979	2.96493
1980	2.70975
1981	2.75572
1982	2.59729
1983	2.40925
1984	1.63476
1985	1.98257
1986	1.98805
1987	1.96525
1988	2.45889
1989	2.24292
1990	2.14725
1991	2.01072
1992	2.03646
1993	2.15754
1994	2.17245
1995	2.29413
1996	2.26841
1997	1.91446
1998	1.69729
1999	1.61578
2000	1.60823
2001	1.47138
2002	1.47389
2003	1.55085
2004	1.36063
2005	1.3318
2006	1.31516
2007	1.34867
2008	1.30366
2009	1.25689
2010	1.22159
2011	1.20525
2012	1.15905
2013	1.2423
2014	1.09041
2015	1.13929
2016	1.22059
2017	1.39056