Year Percent 1980-01-01 0.8385229999999999 1981-01-01 0.9962409999999999 1982-01-01 1.2097700000000000 1983-01-01 1.7701300000000000 1984-01-01 1.7296400000000000 1985-01-01 2.1449500000000000 1986-01-01 2.3572700000000000 1987-01-01 2.5531099999999998 1988-01-01 2.7170900000000002 1989-01-01 2.7928700000000000 1990-01-01 3.1852900000000000 1991-01-01 3.2982600000000000 1992-01-01 3.2327900000000000 1993-01-01 6.2314300000000005 1994-01-01 7.9424899999999990 1995-01-01 8.3908100000000000 1996-01-01 10.8136000000000000 1997-01-01 12.8553000000000000 1998-01-01 16.8786000000000000 1999-01-01 20.6603000000000000 2000-01-01 26.6018000000000000 2001-01-01 29.0914000000000000 2002-01-01 31.5778000000000000 2003-01-01 36.4634000000000000 2004-01-01 34.1838000000000000 2005-01-01 36.9543000000000000 2006-01-01 51.9317000000000000 2007-01-01 61.5863000000000000 2008-01-01 61.3539000000000000 2009-01-01 73.6870000000000000 2010-01-01 71.8331000000000000 2011-01-01 69.3019000000000000 2012-01-01 81.7357000000000000 2013-01-01 81.7498000000000000 2014-01-01 70.6397000000000000 2015-01-01 73.3346000000000000 2016-01-01 63.8389000000000000