Year	Percent
1978	4.73566
1979	6.46459
1980	6.2375
1981	10.48066
1982	20.16299
1983	16.99022
1984	10.85907
1985	10.27643
1986	33.24307
1987	20.43591
1988	15.63191
1989	14.16078
1990	22.23393
1991	13.59873
1992	12.74737
1993	11.54139
1994	14.12573
1995	15.59982
1996	12.54121
1997	11.75822
2003	14.79182
2004	20.98358
2005	15.11595
2006	14.76703
2007	13.38038
2008	5.41326
2009	6.84175
2010	8.60371
2011	10.44544
2012	9.42451
2013	10.9594
2014	17.51015
2015	14.4065
2016	15.168