Year	Percent
1973-01-01	18.40490
1974-01-01	15.71250
1975-01-01	21.29110
1976-01-01	26.21960
1977-01-01	28.79850
1978-01-01	31.89740
1979-01-01	28.92700
1980-01-01	26.14630
1981-01-01	27.23590
1982-01-01	29.90960
1983-01-01	32.17480
1984-01-01	25.73200
1985-01-01	27.00170
1986-01-01	30.24540
1987-01-01	28.91680
1988-01-01	29.27980
1989-01-01	21.01310
1990-01-01	16.77490
1991-01-01	17.19360
1992-01-01	17.57060
1993-01-01	17.54660
1994-01-01	14.15230
1995-01-01	13.09870
1996-01-01	9.05614
1997-01-01	10.94910
1998-01-01	12.86780
1999-01-01	12.40450
2000-01-01	11.86260
2001-01-01	13.60980
2002-01-01	12.98730
2003-01-01	11.79120
2004-01-01	11.57650
2005-01-01	13.34460
2006-01-01	17.48580
2007-01-01	26.91610
2008-01-01	21.68310
2009-01-01	24.92620
2010-01-01	21.94640
2011-01-01	22.57950
2012-01-01	29.08710
2013-01-01	35.46220
2014-01-01	43.30640
2015-01-01	39.83260