Year Percent 1960-01-01 26.81650000000000 1961-01-01 25.92000000000000 1962-01-01 25.94260000000000 1963-01-01 27.10530000000000 1964-01-01 26.84970000000000 1965-01-01 26.79050000000000 1966-01-01 27.19290000000000 1967-01-01 27.63620000000000 1968-01-01 26.95980000000000 1969-01-01 26.05990000000000 1970-01-01 26.37100000000000 1971-01-01 25.62970000000000 1972-01-01 25.30920000000000 1973-01-01 25.13970000000000 1974-01-01 25.11100000000000 1975-01-01 25.51720000000000 1976-01-01 25.51090000000000 1977-01-01 25.09370000000000 1978-01-01 24.51230000000000 1979-01-01 23.17690000000000 1980-01-01 22.81570000000000 1981-01-01 22.20680000000000 1982-01-01 21.07430000000000 1983-01-01 22.02630000000000 1984-01-01 24.17890000000000 1985-01-01 26.69440000000000 1986-01-01 31.08860000000000 1987-01-01 41.56540000000000 1988-01-01 47.97540000000000 1989-01-01 48.14160000000000 1990-01-01 49.32040000000000 1991-01-01 45.09500000000000 1992-01-01 39.89100000000000 1993-01-01 36.65400000000000 1994-01-01 31.06280000000000 1995-01-01 29.53080000000000 1996-01-01 29.67970000000000 1997-01-01 30.12580000000000 1998-01-01 32.23440000000000 1999-01-01 33.35650000000000 2000-01-01 81.49300000000000 2001-01-01 133.66800000000000 2002-01-01 138.93700000000000 2003-01-01 144.28400000000000 2004-01-01 148.17800000000000 2005-01-01 157.53500000000000 2006-01-01 169.58800000000000 2007-01-01 185.87099999999998 2008-01-01 202.69099999999997 2009-01-01 211.92200000000000 2010-01-01 193.57200000000000 2011-01-01 189.82000000000000 2012-01-01 184.02900000000002 2013-01-01 178.54000000000000 2014-01-01 173.47799999999998 2015-01-01 170.75099999999998 2016-01-01 169.06799999999998