Year	Percent
1991	59.33887
1992	59.19341
1993	59.13924
1994	59.26414
1995	59.15696
1996	59.15859
1997	58.95913
1998	58.80111
1999	58.57002
2000	57.87548
2001	57.42274
2002	56.90416
2003	56.36413
2004	55.71867
2005	54.05124
2006	52.37534
2007	50.71872
2008	48.93565
2009	47.1716
2010	45.36555
2011	43.53071
2012	41.75329
2013	39.8978
2014	38.13242
2015	37.40913
2016	36.65626
2017	35.89365
2018	35.18863
2019	34.59629