Year	Measure
1990	0.761
1991	0.759
1992	0.761
1993	0.767
1994	0.776
1995	0.785
1996	0.797
1997	0.802
1998	0.802
1999	0.811
2000	0.821
2001	0.828
2002	0.833
2003	0.839
2004	0.84
2005	0.847
2006	0.851
2007	0.856
2008	0.858
2009	0.859
2010	0.861
2011	0.864
2012	0.865
2013	0.871
2014	0.875
2015	0.878