Year	Measure
1990	0.592
1991	0.595
1992	0.606
1993	0.613
1994	0.62
1995	0.626
1996	0.635
1997	0.643
1998	0.65
1999	0.65
2000	0.653
2001	0.656
2002	0.659
2003	0.658
2004	0.658
2005	0.669
2006	0.675
2007	0.683
2008	0.691
2009	0.695
2010	0.7
2011	0.707
2012	0.712
2013	0.72
2014	0.724
2015	0.727