Year	Percent
1975	1.52618
1976	1.75229
1977	2.07792
1978	4.95813
1979	5.89275
1980	5.69889
1981	6.90258
1982	8.53516
1983	4.79034
1984	4.17931
1985	4.58816
1986	5.83776
1987	5.25325
1988	5.60305
1989	5.64466
1990	5.28479
1991	5.70375
1992	5.87807
1993	5.36986
1994	5.1113
1995	5.18323
1996	5.27394
1997	5.06849
1998	5.3331
1999	5.50362
2000	3.96167
2001	4.14808
2002	4.61111
2003	4.65883
2004	4.04493
2005	3.21439
2006	3.103
2007	2.95698
2008	2.80016
2009	3.61053
2010	3.27776
2011	3.5915
2012	3.84457
2013	4.14144
2014	4.41859
2015	4.63288
2016	4.72571
2017	4.12383