Year Percent 1960-01-01 33.64620000000000 1961-01-01 30.02600000000000 1962-01-01 29.46200000000000 1963-01-01 26.26490000000000 1964-01-01 35.05440000000000 1965-01-01 32.21300000000000 1966-01-01 32.60020000000000 1967-01-01 32.37360000000000 1968-01-01 35.03480000000000 1969-01-01 37.38190000000000 1970-01-01 33.58990000000000 1971-01-01 36.46460000000000 1972-01-01 39.05400000000000 1973-01-01 38.12370000000000 1974-01-01 44.25440000000000 1975-01-01 54.03950000000000 1976-01-01 45.19180000000000 1977-01-01 42.76090000000000 1978-01-01 43.63590000000000 1979-01-01 40.41170000000000 1980-01-01 40.71170000000000 1981-01-01 40.24140000000000 1982-01-01 39.56570000000000 1983-01-01 40.42350000000000 1984-01-01 41.70760000000000 1985-01-01 45.08320000000000 1986-01-01 49.78500000000000 1987-01-01 52.78200000000000 1988-01-01 56.35170000000000 1989-01-01 58.46660000000000 1990-01-01 59.27960000000000 1991-01-01 62.08760000000000 1992-01-01 65.57200000000000 1993-01-01 65.75960000000000 1994-01-01 66.26180000000000 1995-01-01 69.25910000000000 1996-01-01 73.08680000000000 1997-01-01 74.76120000000000 1998-01-01 73.63250000000000 1999-01-01 74.97760000000000 2000-01-01 74.46800000000000 2001-01-01 74.97430000000000 2002-01-01 78.39770000000000 2003-01-01 82.06840000000000 2004-01-01 88.71280000000000 2005-01-01 94.71020000000000 2006-01-01 93.30520000000000 2007-01-01 90.84390000000000 2008-01-01 94.74940000000000 2009-01-01 98.43790000000000 2010-01-01 96.63880000000000 2011-01-01 96.33160000000000 2012-01-01 97.02460000000000 2013-01-01 97.33420000000000 2014-01-01 100.17600000000000 2015-01-01 103.86200000000001 2016-01-01 106.51000000000000