Year	Percent
1991	67.18551
1992	66.20233
1993	64.56485
1994	68.23398
1995	69.63962
1996	68.68056
1997	69.74388
1998	70.06872
1999	70.26113
2000	69.6898
2001	68.92878
2002	67.08558
2003	70.05497
2004	71.19266
2005	71.61604
2006	72.58719
2008	73.64808
2009	73.42246
2010	74.0998
2011	73.87215
2012	74.0489
2013	73.36174
2014	73.36622
2017	71.78896