Year	Measure
1990	0.408
1991	0.408
1992	0.405
1993	0.413
1994	0.416
1995	0.417
1996	0.426
1997	0.432
1998	0.435
1999	0.439
2000	0.443
2001	0.444
2002	0.447
2003	0.45
2004	0.452
2005	0.455
2006	0.458
2007	0.462
2008	0.466
2009	0.47
2010	0.47
2011	0.477
2012	0.483
2013	0.487
2014	0.49
2015	0.493