Year Percent 1980-01-01 0.7281569999999999 1981-01-01 0.6579729999999999 1982-01-01 1.0251400000000000 1983-01-01 1.5831000000000000 1984-01-01 2.4346500000000000 1985-01-01 4.6851500000000000 1986-01-01 7.9488100000000010 1987-01-01 14.5203000000000000 1988-01-01 14.2882000000000000 1989-01-01 15.1501000000000000 1990-01-01 16.7499000000000000 1991-01-01 17.4339000000000000 1992-01-01 17.2861000000000000 1993-01-01 15.3672000000000000 1994-01-01 14.7971000000000000 1995-01-01 15.4216000000000000 1996-01-01 15.7441000000000000 1997-01-01 14.7451000000000000 1998-01-01 17.5595000000000000 1999-01-01 19.2616000000000000 2000-01-01 23.2066000000000000 2001-01-01 26.0506000000000000 2002-01-01 27.8268000000000000 2003-01-01 31.0801000000000000 2004-01-01 35.2271000000000000 2005-01-01 35.6683000000000000 2006-01-01 46.8796000000000000 2007-01-01 46.5128000000000000 2008-01-01 41.7754000000000000 2009-01-01 51.1952000000000000 2010-01-01 43.3521000000000000 2011-01-01 36.2858000000000000 2012-01-01 37.8232000000000000 2013-01-01 41.0960000000000040 2014-01-01 42.1794000000000000 2015-01-01 49.1401000000000000 2016-01-01 48.3721000000000000