Year	Measure
1990	0.762
1991	0.766
1992	0.772
1993	0.78
1994	0.788
1995	0.794
1996	0.801
1997	0.809
1998	0.84
1999	0.848
2000	0.857
2001	0.862
2002	0.87
2003	0.88
2004	0.889
2005	0.896
2006	0.902
2007	0.908
2008	0.909
2009	0.907
2010	0.909
2011	0.895
2012	0.902
2013	0.91
2014	0.92
2015	0.923