Year	Percent
1991	31.075
1992	31.447
1993	31.613
1994	31.899
1995	32.355
1996	32.395
1997	32.716
1998	33.105
1999	33.283
2000	33.845
2001	33.864
2002	31.993
2003	31.605
2004	31.853
2005	35.567
2006	39.472
2007	37.464
2008	35.934
2009	34.455
2010	33.928
2011	30.872
2012	37.707
2013	30.803
2014	30.198
2015	28.059
2016	31.235
2017	31.278
2018	31.284
2019	31.278
2020	31.304
2021	31.344
2022	31.393