Year	Measure
1990	0.731
1991	0.741
1992	0.749
1993	0.759
1994	0.77
1995	0.781
1996	0.792
1997	0.802
1998	0.8
1999	0.811
2000	0.82
2001	0.826
2002	0.835
2003	0.843
2004	0.852
2005	0.86
2006	0.867
2007	0.873
2008	0.876
2009	0.87
2010	0.884
2011	0.889
2012	0.891
2013	0.896
2014	0.899
2015	0.901