Year	Percent
1991	35.006
1992	34.63
1993	34.288
1994	33.761
1995	33.286
1996	32.817
1997	33.407
1998	32.916
1999	33.072
2000	33.276
2001	33.245
2002	33.366
2003	33.537
2004	33.398
2005	32.932
2006	32.478
2007	31.783
2008	32.217
2009	33.117
2010	32.58
2011	33.057
2012	33.92
2013	34.979
2014	35.731
2015	36.246
2016	36.623
2017	36.324
2018	36.017
2019	35.73
2020	35.481
2021	35.282
2022	35.135