Year	Percent
1990	18.43
1991	17.87
1992	18.81
1993	15.43
1994	18.39
1995	20.4
1996	21
1997	19.98
1998	22.28
1999	23.35
2000	20.6
2001	20.36
2002	18.22
2003	17.02
2004	14.41
2005	13.51
2006	12.15
2007	11.47
2008	11.76
2009	11.84
2010	11.96
2011	12.73
2012	12.37
2013	12.39
2014	11.4
2015	11.89
2016	11.67
2017	11.98
2018	12.27
2019	11.73