Year	Percent
1962	0.11329
1963	0.36932
1964	0.65116
1965	1.13294
1966	1.43724
1967	1.62348
1968	1.79408
1969	1.82458
1970	1.97303
1971	3.46866
1972	4.06217
1973	3.49578
1974	3.62484
1975	2.82293
1976	3.18528
1977	2.03607
1978	1.96665
1979	1.6872
1980	2.21723
1981	1.88804
1982	1.97598
1983	2.21854
1984	2.6267
1985	2.66173
1986	2.90592
1987	2.586
1988	2.45988
1989	2.72998
1990	2.96853
1991	2.508
1992	1.65918
1993	1.93137
1994	2.01578
1995	2.10151
1996	2.21091
1997	2.11671
1998	2.44236
1999	2.65573
2000	2.48144
2001	2.32165
2002	2.34346
2003	2.40575
2004	2.53965
2005	2.40749
2006	2.20244
2007	2.0485
2008	1.46663
2009	1.54073
2010	3.07368
2011	2.93953
2012	1.73095
2013	1.65548
2014	1.64253
2015	1.91525
2016	2.06087
2017	1.67507