Year	Percent
1973-01-01	55.775
1974-01-01	57.640
1975-01-01	60.065
1976-01-01	61.260
1977-01-01	63.015
1978-01-01	64.650
1979-01-01	67.925
1980-01-01	66.955
1981-01-01	67.525
1982-01-01	69.285
1983-01-01	68.890
1984-01-01	69.700
1985-01-01	69.040
1986-01-01	66.215
1987-01-01	68.240
1988-01-01	76.515
1989-01-01	85.970
1990-01-01	91.305
1991-01-01	93.130
1992-01-01	100.560
1993-01-01	85.275
1994-01-01	82.370
1995-01-01	82.660
1996-01-01	87.400
1997-01-01	88.900
1998-01-01	69.600
1999-01-01	72.230
2000-01-01	100.040
2001-01-01	83.590
2002-01-01	77.460
2003-01-01	81.670
2004-01-01	91.900
2005-01-01	90.900
2006-01-01	89.990
2007-01-01	95.920
2008-01-01	105.030
2009-01-01	114.130
2010-01-01	112.140
2011-01-01	110.650
2012-01-01	109.720
2013-01-01	108.480
2014-01-01	100.880
2015-01-01	102.985