Year	Percent
1991	78.13137
1992	77.76443
1993	77.6971
1994	78.834
1995	78.36924
1996	77.7522
1997	77.29775
1998	76.75085
1999	75.376
2000	73.47707
2001	68.93373
2002	67.25144
2003	65.98489
2004	63.86544
2005	62.03011
2006	60.07606
2007	58.12695
2008	58.10712
2009	58.0386
2010	57.31127
2011	56.54767
2012	53.20471
2013	49.52275
2014	45.99595
2015	42.4684
2016	37.54026
2017	38.22739
2018	36.39695
2019	34.55346