Year	Percent
1991	52.75614
1992	52.7417
1993	52.72073
1994	52.67183
1995	52.39618
1996	52.05426
1997	51.74703
1998	51.45285
1999	51.22289
2000	51.14582
2001	51.01684
2002	50.88283
2003	50.71068
2004	50.3315
2005	49.93576
2006	49.55177
2007	49.09355
2008	48.60688
2009	48.00538
2010	47.54675
2011	47.44946
2012	46.33989
2013	45.30148
2014	44.49594
2015	43.70612
2016	42.99553
2017	42.02281
2018	41.14126
2019	40.26656