Year	Percent
1991	74.25165
1992	74.281
1993	74.18683
1994	74.07324
1995	73.98945
1996	73.73977
1997	73.4912
1998	73.13106
1999	72.79952
2000	72.64451
2001	71.82903
2002	71.54908
2003	70.99017
2004	70.80243
2005	70.38386
2006	69.96855
2007	69.71976
2008	69.38664
2009	68.99233
2010	68.57541
2011	68.08761
2012	67.95477
2013	67.70324
2014	66.70149
2015	62.26591
2016	64.92684
2017	63.15533
2018	62.98913
2019	62.43593