Year	Percent
1990	28.65
1991	27.61
1992	25.34
1993	24.85
1994	23.79
1995	23.11
1996	22.48
1997	21.83
1998	21.19
1999	20.57
2000	19.98
2001	19.68
2002	19.41
2003	19.15
2004	18.19
2005	17.27
2006	16.09
2007	17.35
2008	12.91
2009	11.11
2010	10.94
2011	10.87
2012	10.82
2013	10.81
2014	10.85
2015	10.87
2016	10.64
2017	10.75
2018	10.81
2019	10.88