Year	Percent
1991	29.46479
1992	30.00541
1993	30.70441
1994	30.53339
1995	29.60189
1996	29.13488
1997	28.53379
1998	28.03301
1999	28.30477
2000	27.38364
2001	26.42294
2002	25.27663
2003	24.50422
2004	24.05139
2005	23.32232
2006	20.54013
2007	20.80791
2008	25.04491
2009	23.87415
2010	22.34368
2011	21.21909
2012	20.96501
2013	21.29001
2014	19.85679
2015	19.4087
2016	18.61215
2017	17.21766
2018	15.92552
2019	15.60432