Year	Percent
1991	37.774
1992	38.012
1993	38.483
1994	38.001
1995	38.968
1996	38.825
1997	37.966
1998	36.131
1999	34.57
2000	33.79
2001	32.775
2002	31.967
2003	32.211
2004	31.457
2005	30.978
2006	31.221
2007	31.837
2008	31.094
2009	29.65
2010	29.655
2011	29.394
2012	26.067
2013	26.172
2014	26.355
2015	26.247
2016	25.823
2017	25.746
2018	25.64
2019	25.474
2020	25.305
2021	25.17
2022	25.063