Year	Percent
1960	0.87158
1961	1.39529
1962	1.75163
1963	1.73684
1964	2.1817
1965	2.10651
1966	1.90023
1967	1.97625
1968	2.07212
1969	1.89474
1970	1.62528
1971	1.60104
1972	1.48779
1973	1.67753
1974	1.44238
1975	1.49291
1976	1.28165
1977	1.67879
1978	1.19431
1979	1.93046
1980	2.03165
1981	1.55137
1982	1.30569
1983	1.62179
1984	2.02029
1985	1.89411
1986	1.96742
1987	2.27827
1988	2.27063
1989	1.89882
1990	1.67438
1999	0.71691
2000	0.61448
2001	0.52465
2002	0.92606
2003	0.97109
2004	1.0314
2005	1.02584
2006	0.99437
2008	0.97575
2012	1.03703
2013	1.03526
2014	1.04318
2015	1.07473
2016	0.90991
2017	1.21632