Year Percent 1973-01-01 5.2538599999999995 1974-01-01 6.0087699999999990 1975-01-01 6.3949900000000000 1976-01-01 6.8278200000000000 1977-01-01 8.5944600000000000 1978-01-01 9.7197900000000000 1979-01-01 10.1298000000000000 1980-01-01 12.0732000000000000 1981-01-01 12.5629999999999990 1982-01-01 13.0012000000000000 1983-01-01 14.2326000000000000 1984-01-01 13.7735000000000000 1985-01-01 14.2253000000000000 1986-01-01 15.7391000000000000 1987-01-01 16.3780000000000000 1988-01-01 16.7919000000000000 1989-01-01 17.7079000000000000 1990-01-01 17.5790000000000000 1991-01-01 18.6605000000000000 1992-01-01 19.3314000000000000 1993-01-01 20.2041000000000000 1994-01-01 21.3038000000000000 1995-01-01 23.8838000000000000 1996-01-01 25.1215000000000000 1997-01-01 24.9477000000000000 1998-01-01 28.4670000000000000 1999-01-01 30.1882000000000000 2000-01-01 31.9130000000000000 2001-01-01 32.5726000000000000 2002-01-01 33.9229000000000000 2003-01-01 34.1513000000000000 2004-01-01 35.0989000000000000 2005-01-01 36.1129000000000000 2006-01-01 38.1526000000000000 2007-01-01 41.5482000000000000 2008-01-01 45.7034000000000000 2009-01-01 54.1823000000000000 2010-01-01 59.7406000000000000 2011-01-01 59.7383000000000000 2012-01-01 62.2739999999999940 2013-01-01 64.6564000000000000 2014-01-01 65.3277000000000000 2015-01-01 69.9065000000000000 2016-01-01 80.9518000000000000