Year	Percent
1991	40.021
1992	40.803
1993	39.611
1994	39.75
1995	39.924
1996	39.288
1997	38.558
1998	34.319
1999	33.379
2000	34.366
2001	33.708
2002	33.668
2003	34.229
2004	34.19
2005	34.017
2006	33.647
2007	33.219
2008	32.773
2009	31.927
2010	32.377
2011	32.052
2012	31.873
2013	32.074
2014	32.466
2015	33.255
2016	33.284
2017	33.203
2018	32.995
2019	32.78
2020	32.578
2021	32.367
2022	32.15