Year	Percent
1991	37.09616
1992	37.1169
1993	36.85152
1994	36.19729
1995	35.74831
1996	35.53042
1997	35.11284
1998	35.08002
1999	35.06888
2000	34.80296
2001	34.6636
2002	34.21427
2003	35.9759
2004	34.24586
2005	34.8212
2006	33.0768
2007	29.43372
2008	28.92256
2009	28.51916
2010	27.73081
2011	28.27657
2012	27.43773
2013	27.41422
2014	28.03316
2015	28.26199
2016	28.37507
2017	27.69259
2018	27.78646
2019	27.3724