Year	Measure
1990	0.611
1991	0.615
1992	0.622
1993	0.631
1994	0.64
1995	0.649
1996	0.656
1997	0.664
1998	0.671
1999	0.677
2000	0.685
2001	0.692
2002	0.699
2003	0.695
2004	0.694
2005	0.698
2006	0.7
2007	0.704
2008	0.714
2009	0.716
2010	0.724
2011	0.73
2012	0.734
2013	0.747
2014	0.754
2015	0.754