Year	Percent
1972-01-01	19.7183
1973-01-01	19.7114
1974-01-01	18.4270
1975-01-01	17.0566
1976-01-01	18.8267
1977-01-01	22.6755
1978-01-01	19.7854
1979-01-01	17.1039
1980-01-01	15.4518
1981-01-01	16.3191
1982-01-01	17.6282
1983-01-01	16.4910
1984-01-01	17.0252
1985-01-01	15.5939
1986-01-01	13.2895
1987-01-01	12.5812
1988-01-01	11.4850
1989-01-01	12.1029
1990-01-01	13.4480
1991-01-01	16.0904
1992-01-01	18.8736
1993-01-01	18.1648
1994-01-01	17.8488
1995-01-01	17.5655
1996-01-01	16.6343
1997-01-01	18.3253
1998-01-01	22.5244
1999-01-01	23.7901
2000-01-01	22.9023
2001-01-01	25.2688
2002-01-01	27.5369
2003-01-01	27.7244
2004-01-01	27.6992
2005-01-01	25.4939
2006-01-01	32.0741
2007-01-01	41.0203
2008-01-01	47.1028
2009-01-01	51.4374
2010-01-01	44.9041
2011-01-01	39.2394
2012-01-01	40.3036
2013-01-01	39.5730
2014-01-01	36.2263
2015-01-01	40.8784
2016-01-01	39.5556