Year	Measure
1990	0.768
1991	0.773
1992	0.779
1993	0.784
1994	0.793
1995	0.799
1996	0.805
1997	0.812
1998	0.818
1999	0.823
2000	0.828
2001	0.836
2002	0.841
2003	0.846
2004	0.851
2005	0.856
2006	0.862
2007	0.866
2008	0.868
2009	0.869
2010	0.872
2011	0.877
2012	0.876
2013	0.877
2014	0.881
2015	0.887