Year	Percent
1999	0.99159
2000	0.98298
2003	0.98129
2004	0.9749
2005	0.97979
2006	0.98402
2007	0.99032
2008	0.99446
2009	0.99934
2010	0.99518
2011	0.98879
2012	0.98977
2013	0.98832
2014	0.98719
2015	0.987
2016	0.98643
2017	0.98592