Year	Percent
1991	36.608
1992	34.252
1993	33.425
1994	32.153
1995	32.778
1996	32.936
1997	34.317
1998	36.837
1999	36.389
2000	36.772
2001	38.468
2002	37.151
2003	38.205
2004	40.299
2005	41.47
2006	41.296
2007	43.149
2008	43.694
2009	43.931
2010	41.132
2011	40.146
2012	39.589
2013	39.753
2014	39.491
2015	37.648
2016	36.494
2017	36.137
2018	36.427
2019	36.554
2020	36.68
2021	36.728
2022	36.746