Year	Percent
1960	1.77337
1961	1.68394
1962	1.68276
1963	1.66807
1964	1.65617
1965	1.61206
1966	1.54135
1967	1.48685
1968	1.29097
1969	1.2166
1970	1.3994
1971	1.3225
1972	1.18327
1973	1.19732
1974	1.0451
1975	0.85349
1976	0.8025
1977	0.6571
1978	0.65145
1979	0.58053
1980	0.45061
1981	0.20065
1982	0.05752
1983	0.06098
1984	0.07708
1985	0.16864
1986	0.26052
1987	0.25327
1988	0.17385
1989	0.18511
1990	0.24029
1991	0.29251
1992	0.36249
1993	0.36495
1994	0.3695
1995	0.55274
1996	0.5977
1997	0.44731
1998	0.39493
1999	0.36144
2000	0.35068
2001	0.41706
2002	0.43685
2003	0.40096
2004	0.49947
2005	0.61384
2006	0.6101
2007	0.66971
2008	0.8121
2009	0.72799
2010	0.60677
2011	0.59821
2012	0.58881
2013	0.58887
2014	0.64214
2015	0.83905
2016	0.91285
2017	0.85464