Year	Percent
1976-01-01	50.5341
1977-01-01	46.9641
1978-01-01	46.0869
1979-01-01	37.7587
1980-01-01	31.8182
1981-01-01	30.4454
1982-01-01	29.0477
1983-01-01	28.7904
1984-01-01	26.1559
1985-01-01	27.8446
1986-01-01	28.9141
1987-01-01	28.6247
1988-01-01	29.0478
1989-01-01	29.2616
1990-01-01	30.1463
1991-01-01	29.6343
1992-01-01	31.7967
1993-01-01	34.8115
1994-01-01	32.4049
1995-01-01	32.1290
1996-01-01	32.2443
1997-01-01	30.9304
1998-01-01	30.4803
1999-01-01	32.8544
2000-01-01	31.9238
2001-01-01	31.9195
2002-01-01	35.1203
2003-01-01	36.3468
2004-01-01	37.4485
2005-01-01	40.0155
2006-01-01	39.9363
2007-01-01	40.1590
2008-01-01	45.3361
2009-01-01	56.4149
2010-01-01	62.4842
2011-01-01	64.6410
2012-01-01	67.7933
2013-01-01	67.8127
2014-01-01	68.5984
2015-01-01	69.1393
2016-01-01	65.7167