Year	Measure
1990	0.703
1991	0.699
1992	0.678
1993	0.668
1994	0.668
1995	0.674
1996	0.68
1997	0.693
1998	0.705
1999	0.716
2000	0.728
2001	0.746
2002	0.761
2003	0.776
2004	0.791
2005	0.807
2006	0.814
2007	0.819
2008	0.821
2009	0.815
2010	0.81
2011	0.812
2012	0.814
2013	0.822
2014	0.828
2015	0.83