Year	Percent
1991	12.009
1992	10.738
1993	12.338
1994	13.419
1995	14.402
1996	15.325
1997	12.691
1998	13.053
1999	13.498
2000	11.827
2001	11.805
2002	12.948
2003	13.01
2004	14.425
2005	11.791
2006	11.779
2007	11.759
2008	11.872
2009	10.07
2010	20.101
2011	20.182
2012	20.231
2013	20.409
2014	20.507
2015	20.282
2016	20.249
2017	20.261
2018	20.24
2019	20.229
2020	20.229
2021	20.224
2022	20.219