Year	Percent
1991	70.692
1992	70.008
1993	69.054
1994	68.885
1995	69.371
1996	69.008
1997	69.55
1998	69.983
1999	70.111
2000	70.541
2001	70.864
2002	71.196
2003	71.387
2004	71.574
2005	71.496
2006	71.667
2007	71.49
2008	71.418
2009	71.277
2010	71.025
2011	69.874
2012	69.46
2013	69.218
2014	68.743
2015	68.43
2016	68.387
2017	68.275
2018	68.178
2019	68.086
2020	68.009
2021	67.932
2022	67.867