Year	Percent
1991	17.465
1992	17.062
1993	14.824
1994	14.076
1995	13.831
1996	13.584
1997	13.306
1998	12.226
1999	12.378
2000	12.128
2001	11.636
2002	11.15
2003	11.034
2004	10.447
2005	9.91
2006	9.836
2007	9.836
2008	9.362
2009	8.616
2010	7.788
2011	7.476
2012	7.389
2013	7.479
2014	7.483
2015	7.954
2016	8.126
2017	8.151
2018	8.137
2019	8.064
2020	7.955
2021	7.828
2022	7.654