Year	Percent
1991	27.678
1992	28.621
1993	28.613
1994	25.986
1995	24.882
1996	24.821
1997	23.543
1998	23.369
1999	24.861
2000	24.894
2001	24.091
2002	22.363
2003	20.622
2004	17.038
2005	14.921
2006	13.251
2007	14.701
2008	15.811
2009	13.772
2010	11.773
2011	9.183
2012	9.351
2013	9.822
2014	10.714
2015	11.404
2016	13.907
2017	13.937
2018	13.951
2019	13.965
2020	13.951
2021	13.94
2022	13.91