Year	Measure
1990	0.712
1991	0.709
1992	0.713
1993	0.723
1994	0.732
1995	0.738
1996	0.746
1997	0.759
1998	0.768
1999	0.777
2000	0.784
2001	0.79
2002	0.796
2003	0.8
2004	0.797
2005	0.803
2006	0.808
2007	0.813
2008	0.818
2009	0.822
2010	0.829
2011	0.834
2012	0.838
2013	0.85
2014	0.852
2015	0.855