Year Percent 1980-01-01 3.132200000000000 1981-01-01 3.891190000000000 1982-01-01 5.138690000000000 1983-01-01 5.747070000000000 1984-01-01 6.292980000000000 1985-01-01 7.729920000000000 1986-01-01 9.529119999999999 1987-01-01 12.350200000000000 1988-01-01 13.366600000000000 1989-01-01 16.565600000000000 1990-01-01 17.511500000000000 1991-01-01 17.321300000000000 1992-01-01 18.751300000000000 1993-01-01 23.150000000000000 1994-01-01 23.261999999999997 1995-01-01 19.815100000000000 1996-01-01 18.946200000000000 1997-01-01 20.460100000000000 1998-01-01 21.310100000000000 1999-01-01 25.987800000000000 2000-01-01 30.360300000000000 2001-01-01 33.631200000000000 2002-01-01 36.005300000000000 2003-01-01 36.784700000000000 2004-01-01 38.399900000000000 2005-01-01 39.030900000000000 2006-01-01 43.449100000000000 2007-01-01 49.264700000000000 2008-01-01 51.608000000000004 2009-01-01 79.467700000000000 2010-01-01 71.186000000000000 2011-01-01 68.388200000000000 2012-01-01 80.414800000000000 2013-01-01 78.606800000000000 2014-01-01 72.487700000000000 2015-01-01 83.082000000000010 2016-01-01 77.950800000000000