Year	Measure
1990	0.681
1991	0.693
1992	0.697
1993	0.7
1994	0.705
1995	0.709
1996	0.714
1997	0.72
1998	0.723
1999	0.727
2000	0.732
2001	0.736
2002	0.74
2003	0.747
2004	0.748
2005	0.752
2006	0.756
2007	0.757
2008	0.757
2009	0.755
2010	0.756
2011	0.706
2012	0.735
2013	0.73
2014	0.719
2015	0.716