Year	Percent
1991	32.974
1992	33.106
1993	33.053
1994	33.131
1995	33.117
1996	31.986
1997	32.049
1998	32.349
1999	32.5
2000	32.493
2001	32.441
2002	32.304
2003	32.201
2004	32.104
2005	32.086
2006	32.127
2007	32.254
2008	32.493
2009	32.532
2010	32.81
2011	33.197
2012	33.46
2013	33.762
2014	33.986
2015	33.975
2016	33.897
2017	33.608
2018	33.194
2019	32.788
2020	32.49
2021	32.317
2022	32.298