Year	Percent
1991	75.66616
1992	75.81578
1993	75.84962
1994	75.81287
1995	75.67482
1996	75.84265
1997	75.74683
1998	75.58884
1999	75.44665
2000	75.50116
2001	75.2566
2002	75.01492
2003	75.16877
2004	74.79651
2005	74.61718
2006	74.21924
2007	73.82761
2008	73.51023
2009	72.92893
2010	72.5041
2011	72.07346
2012	71.57122
2013	72.52555
2014	72.29077
2015	71.82682
2016	71.29576
2017	70.77514
2018	70.29515
2019	69.85476