Year	Percent
1991	75.481
1992	74.858
1993	74.521
1994	74.026
1995	73.556
1996	73.136
1997	72.767
1998	72.371
1999	71.502
2000	70.376
2001	69.44
2002	68.39
2003	67.086
2004	65.713
2005	64.226
2006	62.68
2007	61.157
2008	59.813
2009	58.326
2010	56.938
2011	56.177
2012	55.153
2013	53.963
2014	52.828
2015	51.786
2016	50.869
2017	50.578
2018	50.298
2019	50.054
2020	49.859
2021	49.711
2022	49.614