Year	Measure
1990	0.738
1991	0.733
1992	0.732
1993	0.736
1994	0.742
1995	0.75
1996	0.754
1997	0.756
1998	0.762
1999	0.761
2000	0.763
2001	0.763
2002	0.771
2003	0.776
2004	0.784
2005	0.793
2006	0.802
2007	0.813
2008	0.82
2009	0.822
2010	0.829
2011	0.835
2012	0.838
2013	0.841
2014	0.842
2015	0.845