Year	Percent
1991	57.93745
1992	58.14377
1993	57.6484
1994	57.10743
1995	56.37895
1996	55.97579
1997	56.10709
1998	55.28745
1999	54.06746
2000	52.83294
2001	51.31186
2002	50.15687
2003	49.27355
2004	48.34094
2005	47.38154
2006	46.29605
2007	45.54836
2008	44.65601
2009	44.05171
2010	42.08442
2011	45.6621
2012	45.97835
2013	44.1873
2014	42.21026
2015	41.24075
2016	40.09276
2017	38.06457
2018	37.34809
2019	36.5566