Year	Measure
1990	0.529
1991	0.534
1992	0.546
1993	0.557
1994	0.567
1995	0.577
1996	0.585
1997	0.595
1998	0.604
1999	0.607
2000	0.615
2001	0.621
2002	0.628
2003	0.636
2004	0.644
2005	0.651
2006	0.657
2007	0.659
2008	0.662
2009	0.662
2010	0.666
2011	0.67
2012	0.675
2013	0.676
2014	0.678
2015	0.68