Year	Percent
1990	12.32
1991	12.78
1992	13.88
1993	14.89
1994	16.6
1995	17.39
1996	18.28
1997	17.97
1998	19.11
1999	19.71
2000	19.29
2001	18.24
2002	17.02
2003	16.07
2004	15.11
2005	13.05
2006	11.26
2007	9.71
2008	8.37
2009	7.2
2010	6.2
2011	7.6
2012	6.76
2013	6.95
2014	8.86
2015	10.7
2016	11.38
2017	11.61
2018	6.48
2019	7.51