Year	Percent
1975-01-01	13.01950
1976-01-01	12.61980
1977-01-01	12.34360
1978-01-01	11.90290
1979-01-01	11.62500
1980-01-01	9.42764
1981-01-01	7.73670
1982-01-01	8.32750
1983-01-01	10.53910
1984-01-01	13.12770
1985-01-01	19.05390
1986-01-01	26.96810
1987-01-01	28.91180
1988-01-01	30.94440
1989-01-01	39.34390
1990-01-01	37.45060
1991-01-01	32.03220
1992-01-01	29.67210
1993-01-01	30.51590
1994-01-01	33.62570
1995-01-01	34.10080
1996-01-01	38.37750
1997-01-01	47.09320
1998-01-01	72.85090
1999-01-01	80.54480
2000-01-01	72.09160
2001-01-01	72.57720
2002-01-01	58.65710
2003-01-01	51.40650
2004-01-01	62.81810
2005-01-01	73.10790
2006-01-01	84.00150
2007-01-01	86.56090
2008-01-01	56.98090
2009-01-01	43.10310
2010-01-01	53.57000
2011-01-01	48.90820
2012-01-01	51.57800
2013-01-01	65.68680
2014-01-01	71.01460
2015-01-01	80.38210
2016-01-01	85.02000
2017-01-01	83.82670