Year	Measure
1990	0.801
1991	0.809
1992	0.814
1993	0.822
1994	0.828
1995	0.834
1996	0.84
1997	0.845
1998	0.85
1999	0.855
2000	0.86
2001	0.867
2002	0.872
2003	0.877
2004	0.884
2005	0.892
2006	0.898
2007	0.903
2008	0.906
2009	0.907
2010	0.912
2011	0.916
2012	0.919
2013	0.92
2014	0.924
2015	0.926