Year	Measure
1990	0.58
1991	0.585
1992	0.589
1993	0.596
1994	0.6
1995	0.606
1996	0.613
1997	0.618
1998	0.622
1999	0.625
2000	0.624
2001	0.632
2002	0.642
2003	0.639
2004	0.646
2005	0.648
2006	0.649
2007	0.654
2008	0.663
2009	0.664
2010	0.675
2011	0.679
2012	0.679
2013	0.688
2014	0.692
2015	0.693