Year	Measure
1990	0.458
1991	0.464
1992	0.468
1993	0.474
1994	0.485
1995	0.489
1996	0.499
1997	0.503
1998	0.51
1999	0.519
2000	0.53
2001	0.54
2002	0.551
2003	0.561
2004	0.569
2005	0.575
2006	0.581
2007	0.589
2008	0.596
2009	0.603
2010	0.612
2011	0.623
2012	0.634
2013	0.64
2014	0.645
2015	0.647