Year	Measure
1990	0.641
1991	0.649
1992	0.653
1993	0.658
1994	0.664
1995	0.67
1996	0.675
1997	0.675
1998	0.675
1999	0.681
2000	0.683
2001	0.687
2002	0.689
2003	0.691
2004	0.699
2005	0.695
2006	0.698
2007	0.7
2008	0.704
2009	0.706
2010	0.709
2011	0.714
2012	0.719
2013	0.727
2014	0.734
2015	0.736