Year	Percent
1973-01-01	19.3832
1974-01-01	17.8362
1975-01-01	17.8812
1976-01-01	19.1764
1977-01-01	20.7855
1978-01-01	26.8306
1979-01-01	25.5041
1980-01-01	22.6808
1981-01-01	25.5405
1982-01-01	27.7584
1983-01-01	36.6942
1984-01-01	40.3341
1985-01-01	40.3027
1986-01-01	42.2624
1987-01-01	46.3417
1988-01-01	48.0545
1989-01-01	45.0369
1990-01-01	39.1605
1991-01-01	38.5790
1992-01-01	39.4590
1993-01-01	37.1815
1994-01-01	31.4477
1995-01-01	31.9053
1996-01-01	34.4196
1997-01-01	40.2753
1998-01-01	43.7593
1999-01-01	39.9465
2000-01-01	35.4156
2001-01-01	36.5015
2002-01-01	38.7257
2003-01-01	31.7689
2004-01-01	29.4551
2005-01-01	30.5590
2006-01-01	32.2653
2007-01-01	31.5222
2008-01-01	28.4289
2009-01-01	45.3747
2010-01-01	43.5925
2011-01-01	37.7606
2012-01-01	41.5966
2013-01-01	43.3718
2014-01-01	46.2009
2015-01-01	55.0255
2016-01-01	62.2008