Year Percent 1976-01-01 1.5579300000000000 1977-01-01 1.5730100000000000 1978-01-01 1.5778600000000000 1979-01-01 1.7236300000000000 1980-01-01 1.7142400000000002 1981-01-01 1.7867800000000000 1982-01-01 1.7604200000000000 1983-01-01 2.1535400000000000 1984-01-01 1.9345800000000000 1985-01-01 1.7996700000000000 1986-01-01 1.5621200000000002 1987-01-01 1.5466700000000000 1988-01-01 1.5932000000000000 1989-01-01 1.7420700000000000 1990-01-01 2.0315800000000000 1991-01-01 2.2021599999999997 1992-01-01 2.2050300000000000 1993-01-01 25.6799000000000000 1994-01-01 46.1786000000000000 1995-01-01 47.7727000000000000 1996-01-01 48.7324000000000000 1997-01-01 50.2645000000000000 1998-01-01 46.1695000000000000 1999-01-01 42.4247000000000000 2000-01-01 46.1903000000000000 2001-01-01 49.1422000000000000 2002-01-01 52.6040000000000000 2003-01-01 54.9861000000000000 2004-01-01 57.9394000000000000 2005-01-01 61.7733000000000000 2006-01-01 65.5257000000000000 2007-01-01 67.1977000000000000 2008-01-01 67.7019000000000000 2009-01-01 69.7224000000000000 2010-01-01 72.1782000000000000 2011-01-01 71.9331000000000000 2012-01-01 74.1090000000000000 2013-01-01 79.1494000000000000 2014-01-01 86.2487000000000000 2015-01-01 90.2332000000000000 2016-01-01 93.3311000000000000