Year	Percent
1991	57.09141
1992	58.05212
1993	57.46195
1994	57.24365
1995	57.2737
1996	58.80272
1997	58.95004
1998	60.12574
1999	59.54748
2000	59.92831
2001	57.06594
2002	57.42406
2003	57.96089
2004	59.14009
2005	58.591
2006	59.10836
2007	59.78213
2008	60.08352
2009	60.25357
2010	61.09968
2011	60.81402
2012	62.47754
2013	63.30986
2014	63.36186
2016	64.94025
2017	65.65547