Year	Measure
1990	0.33
1991	0.336
1992	0.34
1993	0.345
1994	0.348
1995	0.351
1996	0.357
1997	0.363
1998	0.369
1999	0.377
2000	0.384
2001	0.392
2002	0.395
2003	0.404
2004	0.412
2005	0.415
2006	0.42
2007	0.426
2008	0.434
2009	0.439
2010	0.441
2011	0.44
2012	0.445
2013	0.449
2014	0.45
2015	0.452