Year	Percent
1990	7.95
1991	8.21
1992	8.59
1993	8.92
1994	13.61
1996	15.45
1997	15.51
1998	17.13
1999	19.84
2000	19.86
2001	19.86
2002	22.45
2003	22.08
2004	24.42
2005	26.22
2006	24.54
2007	22.6
2008	19.53
2009	18.89
2010	17.56
2011	18.4
2012	15.49
2013	15.73
2014	15.72
2015	17.03
2016	15.82
2017	14.45
2018	16.28
2019	13.55
2020	14.76