Year Percent 1980-01-01 2.0990800000000000 1981-01-01 2.0777500000000000 1982-01-01 2.9663200000000000 1983-01-01 3.5342700000000000 1984-01-01 3.5751600000000000 1985-01-01 7.3938500000000000 1986-01-01 5.9915699999999990 1987-01-01 6.8757199999999990 1988-01-01 6.5326400000000000 1989-01-01 5.7463200000000000 1990-01-01 5.2372300000000000 1991-01-01 6.2129400000000010 1992-01-01 6.3797400000000000 1993-01-01 7.7101100000000000 1994-01-01 8.7372900000000000 1995-01-01 7.9735000000000000 1996-01-01 5.9315300000000000 1997-01-01 5.2249200000000000 1998-01-01 6.6613700000000000 1999-01-01 7.0011700000000000 2000-01-01 4.8122300000000005 2001-01-01 4.2942800000000005 2002-01-01 5.6464200000000000 2003-01-01 7.5322600000000010 2004-01-01 8.4106300000000010 2005-01-01 10.0784000000000000 2006-01-01 10.8107000000000000 2007-01-01 12.1162000000000000 2008-01-01 12.5885000000000000 2009-01-01 20.3822000000000000 2010-01-01 19.6742000000000000 2011-01-01 18.8392000000000000 2012-01-01 20.0780000000000000 2013-01-01 24.2992000000000000 2014-01-01 25.3147000000000000 2015-01-01 30.3493000000000000 2016-01-01 34.1708000000000000