Year	Percent
1984	55.09329
1986	48.02193
1987	52.90181
1988	52.26181
1989	52.38011
1990	52.56997
1994	53.93191
2000	73.46481
2001	71.59488
2002	68.42952
2004	70.84355
2005	71.67716
2006	71.70954
2007	71.54351
2008	71.88138
2009	72.11839
2010	72.76478
2011	74.00435
2012	74.53141
2013	74.27124
2014	74.47605
2015	73.99419
2016	73.46403
2017	73.09317