Year Percent 1982-01-01 16.19120000000000 1983-01-01 17.03380000000000 1984-01-01 18.81410000000000 1985-01-01 20.68440000000000 1986-01-01 21.75950000000000 1987-01-01 36.69090000000000 1988-01-01 51.19460000000000 1989-01-01 52.12340000000000 1990-01-01 48.30020000000000 1991-01-01 42.50910000000000 1992-01-01 40.90570000000000 1993-01-01 41.68070000000000 1994-01-01 42.40060000000000 1995-01-01 40.76360000000000 1996-01-01 42.60820000000000 1997-01-01 48.97300000000000 1998-01-01 53.69390000000000 1999-01-01 58.74020000000000 2000-01-01 67.01660000000000 2001-01-01 75.63140000000000 2002-01-01 83.52360000000000 2003-01-01 89.93190000000000 2004-01-01 94.16360000000000 2005-01-01 96.96000000000000 2006-01-01 98.35190000000000 2007-01-01 98.86590000000000 2008-01-01 98.76180000000000 2009-01-01 98.48870000000000 2010-01-01 98.68590000000000 2011-01-01 98.97200000000001 2012-01-01 99.19240000000000 2013-01-01 99.22160000000000 2014-01-01 99.21540000000000 2015-01-01 99.46520000000000 2016-01-01 99.75990000000000