Year	Percent
1997	52.09218
1998	52.95627
1999	54.10655
2000	55.26332
2001	55.20054
2002	57.43686
2003	58.95441
2004	58.5196
2005	58.45644
2006	56.29822
2007	59.93998
2008	59.28024
2009	63.47445
2010	60.30755
2011	59.68846
2012	60.44493
2013	61.34239
2014	61.33023
2015	61.95766
2016	62.96135