Year	Percent
1977	1.0396
1978	1.28253
1979	2.17389
1980	4.14561
1981	9.19604
1982	16.22599
1983	23.61052
1984	32.94432
1985	32.78037
1986	38.03891
1987	14.13063
1988	30.36505
1989	24.69282
1990	22.59629
1991	22.05631
1992	18.57413
1993	13.39577
1994	18.94678
1995	14.73073
1996	13.13697
1997	8.71204
1998	13.07433
1999	7.60561
2000	8.75612
2001	12.72083
2002	8.06113
2003	5.92562
2004	4.4702
2005	15.41075
2006	10.98079
2007	1.44237
2008	0.75913
2009	1.27643
2010	1.50173
2011	0.50821
2012	1.34419
2013	0.49417
2014	5.31548
2015	2.86872
2016	6.30461