Year	Percent
1991	81.113
1992	80.629
1993	80.128
1994	79.621
1995	79.142
1996	78.668
1997	78.189
1998	77.703
1999	77.12
2000	76.527
2001	75.934
2002	75.329
2003	74.691
2004	73.485
2005	72.234
2006	72.354
2007	70.64
2008	68.787
2009	66.862
2010	64.874
2011	62.834
2012	60.741
2013	58.6
2014	56.398
2015	56.077
2016	55.751
2017	55.445
2018	55.139
2019	54.835
2020	54.537
2021	54.247
2022	53.952