Year Percent 1980-01-01 1.4032400000000000 1981-01-01 1.6933700000000000 1982-01-01 1.8930099999999999 1983-01-01 1.7626500000000000 1984-01-01 1.5628799999999998 1985-01-01 2.5911600000000000 1986-01-01 2.9878200000000000 1987-01-01 3.9682600000000000 1988-01-01 5.0611900000000000 1989-01-01 6.2603900000000000 1990-01-01 7.1636800000000000 1991-01-01 11.0296000000000000 1992-01-01 11.2464000000000000 1993-01-01 15.0018000000000000 1994-01-01 16.8848000000000000 1995-01-01 18.9004000000000000 1996-01-01 22.7295000000000000 1997-01-01 26.5805000000000000 1998-01-01 29.3990000000000000 1999-01-01 29.3354000000000000 2000-01-01 34.0027000000000000 2001-01-01 34.4750000000000000 2002-01-01 39.6943000000000000 2003-01-01 41.9090000000000000 2004-01-01 42.2950000000000000 2005-01-01 39.6922000000000000 2006-01-01 50.2984000000000000 2007-01-01 56.2075000000000000 2008-01-01 55.7608000000000000 2009-01-01 71.0795000000000000 2010-01-01 73.3173000000000000 2011-01-01 59.2784000000000000 2012-01-01 62.9756000000000000 2013-01-01 65.9743000000000000 2014-01-01 53.1352000000000000 2015-01-01 59.6553000000000000 2016-01-01 58.6713000000000000