Year	Percent
1991	59.898
1992	59.919
1993	56.159
1994	55.133
1995	50.757
1996	48.769
1997	49.373
1998	52.258
1999	49.833
2000	49.834
2001	48.023
2002	47.875
2003	46.868
2004	43.983
2005	44.225
2006	43.512
2007	43.313
2008	44.338
2009	41.058
2010	40.101
2011	42.571
2012	43.668
2013	41.607
2014	35.358
2015	34.346
2016	35.369
2017	34.928
2018	34.178
2019	33.446
2020	32.744
2021	32.044
2022	31.375