Year	Percent
1991	24.88789
1992	24.73684
1993	24.56272
1994	24.37
1995	24.13643
1996	23.87409
1997	23.54039
1998	23.18271
1999	22.85452
2000	22.33531
2001	21.71157
2002	21.72261
2003	21.7172
2004	20.10131
2005	18.54105
2006	17.05771
2007	15.6301
2008	14.32522
2009	13.02977
2010	11.86927
2011	10.76882
2012	10.69365
2013	10.58487
2014	10.48683
2015	10.31116
2016	10.15082
2017	9.97684
2018	9.6964
2019	9.4388