Year	Measure
1990	0.706
1991	0.701
1992	0.693
1993	0.682
1994	0.668
1995	0.664
1996	0.661
1997	0.663
1998	0.665
1999	0.669
2000	0.673
2001	0.683
2002	0.691
2003	0.7
2004	0.707
2005	0.716
2006	0.723
2007	0.73
2008	0.734
2009	0.728
2010	0.734
2011	0.739
2012	0.744
2013	0.746
2014	0.748
2015	0.743