Year	Percent
1991	88.238
1992	89.064
1993	88.437
1994	87.921
1995	87.144
1996	86.114
1997	85.68
1998	84.928
1999	83.374
2000	82.411
2001	81.101
2002	79.718
2003	78.716
2004	77.134
2005	75.37
2006	75.282
2007	74.653
2008	74.392
2009	73.647
2010	71.506
2011	68.868
2012	67.853
2013	64.617
2014	63.002
2015	61.251
2016	60.254
2017	59.397
2018	58.234
2019	57.278
2020	56.321
2021	55.39
2022	54.49