Year	Percent
1980-01-01	10.0693
1981-01-01	52.4072
1982-01-01	76.2056
1983-01-01	65.0376
1984-01-01	58.0111
1985-01-01	54.1861
1986-01-01	51.4991
1987-01-01	47.2426
1988-01-01	34.4305
1989-01-01	20.7952
1990-01-01	16.1884
1991-01-01	22.7566
1992-01-01	25.3874
1993-01-01	25.4671
1994-01-01	24.1073
1995-01-01	24.3364
1996-01-01	26.5967
1997-01-01	28.0939
1998-01-01	29.8699
1999-01-01	32.1524
2000-01-01	33.4994
2001-01-01	36.9360
2002-01-01	46.2156
2003-01-01	53.4741
2004-01-01	45.7764
2005-01-01	38.9892
2006-01-01	40.9677
2007-01-01	44.8627
2008-01-01	54.5507
2009-01-01	60.7310
2010-01-01	60.8808
2011-01-01	62.1171
2012-01-01	63.4222
2013-01-01	63.7717
2014-01-01	65.8630
2015-01-01	67.8125
2016-01-01	70.4175