Year	Percent
1991	32.942
1992	33.191
1993	33.199
1994	33.317
1995	33.363
1996	33.25
1997	33.422
1998	33.135
1999	32.971
2000	33.208
2001	32.837
2002	33.134
2003	33.147
2004	33.435
2005	33.254
2006	33.338
2007	33.095
2008	32.539
2009	31.9
2010	32.82
2011	32.774
2012	32.595
2013	32.709
2014	32.573
2015	32.672
2016	32.646
2017	32.523
2018	32.517
2019	32.51
2020	32.504
2021	32.498
2022	32.493