Year	Measure
1971	0.03872
1972	0.05528
1973	0.05198
1974	0.06909
1975	0.07345
1976	0.07705
1977	0.07874
1978	0.07015
1979	0.07334
1980	0.04728
1981	0.04402
1982	0.03858
1983	0.03643
1984	0.03067
1985	0.02773
1986	0.02219
1987	0.01
1988	0.02404
1989	0.02815
1990	0.03588
1991	0.02522
1992	0.0247
1993	0.01577
1994	0.01571
1995	0.01681
1996	0.01564
1997	0.0151
1998	0.01351
1999	0.02045
2000	0.02241
2001	0.0205
2002	0.02608
2003	0.03653
2004	0.03768
2005	0.03991
2006	0.0294
2007	0.02945
2008	0.02429
2009	0.0257
2010	0.0278