Year	Percent
1991	68.226
1992	68.151
1993	67.89
1994	68.093
1995	67.538
1996	67.364
1997	67.521
1998	67.215
1999	66.773
2000	66.831
2001	66.435
2002	66.119
2003	65.626
2004	65.258
2005	64.805
2006	64.366
2007	64.196
2008	63.883
2009	63.578
2010	63.095
2011	62.724
2012	62.329
2013	62.131
2014	61.988
2015	62.018
2016	61.979
2017	61.9
2018	61.824
2019	61.757
2020	61.711
2021	61.647
2022	61.57