Year	Percent
1991	68.954
1992	67.925
1993	67.494
1994	66.548
1995	67.604
1996	66.451
1997	66.401
1998	65.95
1999	65.871
2000	66.161
2001	67.206
2002	65.427
2003	65.267
2004	64.028
2005	63.312
2006	63.415
2007	63.153
2008	62.461
2009	61.602
2010	61.97
2011	62.755
2012	62.26
2013	62.158
2014	62.696
2015	63.146
2016	63.956
2017	64.019
2018	63.862
2019	63.661
2020	63.417
2021	63.136
2022	62.825