Year	Percent
1991	44.713
1992	46.373
1993	44.834
1994	46.235
1995	41.563
1996	40.385
1997	41.236
1998	38.872
1999	38.295
2000	36.156
2001	36.594
2002	37.032
2003	36.801
2004	36.701
2005	35.613
2006	34.738
2007	34.418
2008	33.583
2009	34.3
2010	33.386
2011	33.643
2012	32.945
2013	32.912
2014	32.186
2015	32.077
2016	31.647
2017	31.617
2018	31.534
2019	31.504
2020	31.459
2021	31.394
2022	31.318