Year	Percent
1991	32.302
1992	32.509
1993	31.608
1994	30.933
1995	31.58
1996	32.229
1997	32.589
1998	33.341
1999	32.765
2000	33.234
2001	33.108
2002	33.404
2003	34.027
2004	34.883
2005	34.419
2006	35.681
2007	36.732
2008	37.608
2009	36.652
2010	36.943
2011	37.721
2012	37.015
2013	37.186
2014	37.048
2015	37.216
2016	37.415
2017	37.176
2018	37.1
2019	37.088
2020	36.77
2021	36.681
2022	36.68