Year	Measure
1990	0.37
1991	0.37
1992	0.368
1993	0.368
1994	0.367
1995	0.368
1996	0.369
1997	0.371
1998	0.377
1999	0.384
2000	0.391
2001	0.399
2002	0.41
2003	0.42
2004	0.432
2005	0.446
2006	0.457
2007	0.468
2008	0.478
2009	0.488
2010	0.498
2011	0.504
2012	0.513
2013	0.512
2014	0.519
2015	0.531