Year	Measure
1971	0.0023
1972	0.00207
1973	0.00259
1974	0.0027
1975	0.00316
1976	0.00373
1977	0.00359
1978	0.0028
1979	0.00387
1980	0.00317
1981	0.00265
1982	0.00267
1983	0.0021
1984	0.00274
1985	0.0031
1986	0.00354
1987	0.00313
1988	0.00372
1989	0.00374
1990	0.00387
1991	0.0051
1992	0.00509
1993	0.00457
1994	0.00445
1995	0.0043
1996	0.0042
1997	0.00417
1998	0.00421
1999	0.00438
2000	0.00391
2001	0.00401
2002	0.00545
2003	0.00481
2004	0.00511
2005	0.00478
2006	0.00376
2007	0.00364
2008	0.00327
2009	0.00252
2010	0.00346