Year	Percent
1991	42.906
1992	39.519
1993	35.718
1994	34.847
1995	34.626
1996	33.94
1997	32.524
1998	34.07
1999	33.194
2000	34.434
2001	34.327
2002	35.247
2003	35.359
2004	35.683
2005	35.195
2006	37.823
2007	41.084
2008	41.133
2009	34.138
2010	33.472
2011	32.339
2012	33.153
2013	34.465
2014	34.898
2015	34.678
2016	35.243
2017	35.24
2018	35.079
2019	34.945
2020	34.8
2021	34.67
2022	34.54