Year	Measure
1990	0.576
1991	0.58
1992	0.586
1993	0.594
1994	0.596
1995	0.604
1996	0.613
1997	0.621
1998	0.632
1999	0.641
2000	0.653
2001	0.658
2002	0.668
2003	0.675
2004	0.681
2005	0.687
2006	0.697
2007	0.705
2008	0.709
2009	0.715
2010	0.737
2011	0.75
2012	0.754
2013	0.759
2014	0.764
2015	0.767