Year	Percent
1975-01-01	45.7317
1976-01-01	40.5123
1977-01-01	38.0675
1978-01-01	36.0350
1979-01-01	34.2785
1980-01-01	33.7369
1981-01-01	33.9390
1982-01-01	41.0581
1983-01-01	43.3921
1984-01-01	39.1223
1985-01-01	40.3071
1986-01-01	41.7476
1987-01-01	46.2301
1988-01-01	47.3896
1989-01-01	51.0517
1990-01-01	49.7757
1991-01-01	51.7406
1992-01-01	49.9482
1993-01-01	51.2642
1994-01-01	51.7441
1995-01-01	52.9686
1996-01-01	55.6257
1997-01-01	57.4006
1998-01-01	57.2232
1999-01-01	59.0113
2000-01-01	62.4182
2001-01-01	69.6786
2002-01-01	69.2447
2003-01-01	67.2477
2004-01-01	67.9128
2005-01-01	70.0819
2006-01-01	71.1077
2007-01-01	70.3999
2008-01-01	75.6639
2009-01-01	80.7211
2010-01-01	77.5662
2011-01-01	74.9612
2012-01-01	76.8874
2013-01-01	76.2093
2014-01-01	77.0341
2015-01-01	74.6495
2016-01-01	75.5724