Year	Measure
1990	0.814
1991	0.819
1992	0.822
1993	0.828
1994	0.834
1995	0.838
1996	0.842
1997	0.846
1998	0.848
1999	0.852
2000	0.856
2001	0.86
2002	0.863
2003	0.866
2004	0.87
2005	0.873
2006	0.877
2007	0.88
2008	0.881
2009	0.879
2010	0.884
2011	0.889
2012	0.894
2013	0.899
2014	0.902
2015	0.903