Year	Percent
1991	44.26146
1992	44.0431
1993	43.53127
1994	42.99377
1995	42.38053
1996	41.82271
1997	41.1513
1998	40.55742
1999	40.47635
2000	40.11629
2001	39.56868
2002	39.11531
2003	38.5848
2004	38.11012
2005	37.55163
2006	37.21464
2007	36.54425
2008	36.26258
2009	35.84462
2010	35.18065
2011	34.51762
2012	33.89768
2013	33.27206
2014	32.68014
2015	32.10512
2016	31.5664
2017	31.07937
2018	30.55103
2019	29.86426