Year	Measure
1971	12.30922
1972	17.02019
1973	19.95703
1974	22.78155
1975	29.37539
1976	26.72651
1977	30.32902
1978	34.30847
1979	35.75108
1980	40.95741
1981	47.77723
1982	48.19263
1983	49.20701
1984	49.51662
1985	50.59369
1986	53.77215
1987	52.46929
1988	53.86485
1989	56.20804
1990	58.31206
1991	44.59237
1992	39.93516
1993	28.2842
1994	18.50184
1995	29.92402
1996	33.51933
1997	41.66692
1998	36.56846
1999	38.78921
2000	35.44191
2001	34.85737
2002	30.33482
2003	28.51875
2004	28.07271
2005	37.02743
2006	37.40917
2007	25.32205
2008	23.59601
2009	35.72563
2010	24.40093
2011	31.14818
2012	45.97049
2013	43.7126
2014	38.96915