Year	Percent
1991	39.299
1992	39.501
1993	39.465
1994	39.357
1995	38.592
1996	38.672
1997	38.62
1998	38.011
1999	37.68
2000	37.156
2001	35.841
2002	35.543
2003	35.398
2004	34.73
2005	34.236
2006	34.631
2007	35.755
2008	35.092
2009	33.016
2010	32.792
2011	32.205
2012	32.432
2013	29.585
2014	29.425
2015	30.421
2016	31.863
2017	31.69
2018	31.537
2019	31.495
2020	31.429
2021	31.249
2022	31.228