Year	Measure
1990	0.574
1991	0.583
1992	0.59
1993	0.598
1994	0.604
1995	0.611
1996	0.619
1997	0.625
1998	0.63
1999	0.64
2000	0.649
2001	0.657
2002	0.666
2003	0.674
2004	0.682
2005	0.686
2006	0.687
2007	0.7
2008	0.706
2009	0.711
2010	0.72
2011	0.729
2012	0.733
2013	0.737
2014	0.738
2015	0.74