Year	Percent
1991	11.766
1992	12.926
1993	13.267
1994	14.359
1995	15.793
1996	16.106
1997	12.206
1998	13.47
1999	14.523
2000	15.047
2001	15.339
2002	15.917
2003	17.442
2004	16.965
2005	16.038
2006	16.157
2007	16.192
2008	16.136
2009	16.778
2010	17.747
2011	18.076
2012	18.439
2013	17.887
2014	18.018
2015	17.361
2016	17.181
2017	17.491
2018	17.345
2019	17.296
2020	17.291
2021	17.296
2022	17.291