Year	Percent
1991	24.96425
1992	24.71332
1993	24.53586
1994	24.28503
1995	23.98365
1996	23.50781
1997	23.84742
1998	24.11541
1999	24.28657
2000	24.39965
2001	24.47395
2002	24.50285
2003	24.53148
2004	24.65014
2005	24.7498
2006	23.17623
2007	22.81141
2008	21.21121
2009	20.86209
2010	19.22192
2011	18.81177
2012	18.49096
2013	18.24403
2014	17.89358
2015	18.03361
2016	17.9836
2017	17.58352
2018	17.69354
2019	17.36411