Year	Percent
1991	29.875
1992	29.201
1993	33.304
1994	35.552
1995	48.94
1996	54.155
1997	52.92
1998	49.245
1999	48.927
2000	47.899
2001	46.499
2002	44.644
2003	44.646
2004	42.068
2005	44.12
2006	44.068
2007	42.962
2008	43.106
2009	42.483
2010	42.411
2011	45.288
2012	44.1
2013	43.822
2014	42.769
2015	40.575
2016	39.505
2017	40.632
2018	40.148
2019	39.57
2020	38.906
2021	38.225
2022	37.538