Year	Percent
1991	74.143
1992	73.383
1993	72.571
1994	71.74
1995	70.89
1996	70.006
1997	69.114
1998	68.184
1999	67.167
2000	66.136
2001	65.044
2002	63.949
2003	62.805
2004	61.285
2005	59.735
2006	60.236
2007	58.678
2008	57.786
2009	56.926
2010	56.035
2011	55.191
2012	54.353
2013	53.534
2014	52.7
2015	52.756
2016	52.943
2017	52.851
2018	52.742
2019	52.619
2020	52.482
2021	52.334
2022	52.174