Year	Percent
1973-01-01	4.4698800000000000
1974-01-01	5.2426699999999995
1975-01-01	12.8114000000000000
1976-01-01	14.9738000000000000
1977-01-01	13.9320000000000000
1978-01-01	14.8570000000000010
1979-01-01	16.7277000000000000
1980-01-01	19.7854000000000000
1981-01-01	26.7689000000000000
1982-01-01	28.8127000000000000
1983-01-01	31.8265000000000000
1984-01-01	27.5923000000000000
1985-01-01	27.0300000000000000
1986-01-01	29.0506000000000000
1987-01-01	26.8743000000000000
1988-01-01	27.4185000000000000
1989-01-01	26.2655000000000000
1990-01-01	21.9015000000000000
1991-01-01	16.6635000000000000
1992-01-01	14.6445000000000000
1993-01-01	11.7569000000000000
1994-01-01	11.7846000000000000
1995-01-01	11.1510000000000000
1996-01-01	11.0550000000000000
1997-01-01	9.3853000000000000
1998-01-01	8.1455600000000010
1999-01-01	9.6154800000000000
2000-01-01	11.1924000000000000
2001-01-01	11.7883000000000000
2002-01-01	12.1391000000000000
2003-01-01	13.9399000000000000
2004-01-01	15.2659999999999980
2005-01-01	16.1130000000000000
2006-01-01	17.1221000000000000
2007-01-01	19.3239000000000000
2008-01-01	23.3506000000000000
2009-01-01	26.0044000000000000
2010-01-01	27.4294000000000000
2011-01-01	28.5140000000000000
2012-01-01	28.5487000000000000
2013-01-01	28.1385000000000000
2014-01-01	29.4571000000000000
2015-01-01	31.3776000000000000
2016-01-01	31.6206000000000000