Year	Percent
1985	12.11
1987	15.89
1988	15.04
1989	17.04
1990	15.39
1991	17.6
1992	17.2
1993	17.26
1994	17.01
1995	16.14
1996	14.47
1997	15.7
1998	18.91
1999	21.31
2001	9.74
2003	9.25
2004	9.38
2005	9.55
2006	10.23
2007	8.94
2008	10.06
2009	10.36
2010	9.94
2011	9.63
2012	9.47
2013	9.23
2014	9.48
2015	8.47
2016	7.7
2017	7.46
2018	6.67
2019	6.77
2020	7.03