Year	Percent
1991	19.336
1992	19.322
1993	18.43
1994	17.847
1995	17.102
1996	15.926
1997	15.667
1998	13.518
1999	13.048
2000	11.783
2001	10.864
2002	10.955
2003	9.953
2004	9.931
2005	9.415
2006	8.941
2007	8.64
2008	8.575
2009	8.18
2010	7.544
2011	7.49
2012	7.664
2013	9.248
2014	9.2
2015	9.085
2016	9.143
2017	8.744
2018	8.619
2019	8.492
2020	8.358
2021	8.226
2022	8.114