Year	Percent
1991	33.789
1992	33.313
1993	32.694
1994	32.785
1995	33.333
1996	33.069
1997	33.152
1998	33.146
1999	32.944
2000	33.242
2001	34.811
2002	33.904
2003	33.409
2004	34.498
2005	34.283
2006	34.225
2007	35.007
2008	35.052
2009	34.376
2010	32.825
2011	32.605
2012	31.861
2013	32.113
2014	32.204
2015	33.147
2016	32.087
2017	32.03
2018	32.039
2019	32.05
2020	31.999
2021	32.054
2022	32.085