Year	Percent
1975	14.69
1976	12.75
1977	11.83
1978	14.26
1979	13.63
1980	10.46
1981	11.35
1982	19.6
1983	14.65
1984	13.91
1986	8.71
1988	6.23
1989	5.29
1990	5.63
1991	5.23
1992	4.35
1993	4.49
1994	5.87
1995	4.7
1996	7.41
1997	7.14
1998	7.31
1999	11.16
2000	10.49
2001	10.39
2002	10.17
2003	9.77
2004	10.16
2005	9.34
2006	9.02
2007	8.43
2008	9.29
2009	11.31
2010	8.42
2011	7.34
2012	6.66
2013	6.21
2014	6.66
2015	6.51
2016	6.74
2017	6.96
2018	7.23
2019	7.29
2020	11.18