Year	Percent
1991	45.497
1992	46.931
1993	45.346
1994	42.187
1995	42.252
1996	41.634
1997	42.24
1998	41.897
1999	41.036
2000	35.832
2001	35.952
2002	35.681
2003	36.071
2004	36.022
2005	34.568
2006	34.719
2007	33.048
2008	32.649
2009	31.866
2010	32.294
2011	32.994
2012	33.409
2013	33.474
2014	33.138
2015	34.526
2016	33.704
2017	33.471
2018	33.441
2019	33.376
2020	33.268
2021	33.232
2022	33.252