Year	Percent
1991	73.495
1992	73.792
1993	73.839
1994	73.638
1995	72.653
1996	72.995
1997	72.493
1998	70.771
1999	71.689
2000	70.732
2001	71.151
2002	70.522
2003	70.173
2004	70.388
2005	69.521
2006	70.622
2007	70.538
2008	69.331
2009	69.195
2010	68.995
2011	68.722
2012	68.264
2013	68.044
2014	67.61
2015	67.353
2016	67.309
2017	67.059
2018	67.099
2019	67.132
2020	68.358
2021	68.869
2022	68.901