Year Percent 1982-01-01 0.64872200000000000 1983-01-01 0.46187600000000000 1984-01-01 0.41645100000000000 1985-01-01 0.45348800000000000 1986-01-01 0.62113300000000000 1987-01-01 0.38769300000000000 1988-01-01 0.16268700000000000 1989-01-01 0.08314600000000000 1990-01-01 0.13328299999999998 1991-01-01 0.32574699999999995 1992-01-01 0.61159300000000000 1993-01-01 0.88722900000000000 1994-01-01 1.63164000000000000 1995-01-01 1.82925999999999990 1996-01-01 2.86249000000000000 1997-01-01 3.32183000000000030 1998-01-01 3.57326000000000000 1999-01-01 4.70547000000000000 2000-01-01 4.41605000000000000 2001-01-01 5.41889000000000000 2002-01-01 6.51098000000000000 2003-01-01 8.39361000000000000 2004-01-01 6.68558000000000000 2005-01-01 5.21506000000000000 2006-01-01 5.29217000000000000 2007-01-01 4.79688000000000100 2008-01-01 4.06278000000000000 2009-01-01 5.25981000000000000 2010-01-01 5.44028000000000040 2011-01-01 5.82280000000000000 2012-01-01 8.30313999999999900 2013-01-01 9.30276999999999900 2014-01-01 10.39720000000000000 2015-01-01 13.00690000000000000 2016-01-01 13.01040000000000000