Year	Percent
1990	32.36
1991	31.52
1992	30.64
1993	29.74
1994	28.83
1995	27.9
1996	26.94
1997	25.97
1998	24.99
1999	24.01
2000	23.03
2001	22.09
2002	21.19
2003	20.32
2004	19.48
2005	18.67
2006	17.77
2007	16.92
2008	16.11
2009	15.35
2010	14.62
2011	13.96
2012	13.31
2013	12.69
2014	12.11
2015	11.57
2016	11.12
2017	10.69
2018	10.56
2019	10.42