Year	Measure
1971	475.66068
1972	473.90469
1973	474.37442
1974	473.92504
1975	471.9523
1976	471.82781
1977	471.41783
1978	472.62081
1979	473.16008
1980	473.45998
1981	474.08221
1982	472.79818
1983	473.19598
1984	471.92902
1985	471.79388
1986	473.40219
1987	476.00329
1988	475.60615
1989	476.00214
1990	476.92443
1991	476.10161
1992	470.45481
1993	472.87349
1994	474.40626
1995	475.84343
1996	476.70612
1997	475.71093
1998	476.09614
1999	475.47544
2000	476.24576
2001	480.06117
2002	480.25726
2003	481.54555
2004	482.13021
2005	480.50922
2006	481.72173
2007	483.64225
2008	485.18881
2009	485.69289
2010	486.34232
2011	489.6818
2012	490.69038
2013	494.72845
2014	496.8146