Year Percent 1960-01-01 29.66240000000000 1961-01-01 28.38100000000000 1962-01-01 28.13140000000000 1963-01-01 28.06140000000000 1964-01-01 28.45050000000000 1965-01-01 29.45170000000000 1966-01-01 28.75180000000000 1967-01-01 27.67870000000000 1968-01-01 27.45890000000000 1969-01-01 27.11270000000000 1970-01-01 24.72360000000000 1971-01-01 26.94250000000000 1972-01-01 30.93140000000000 1973-01-01 32.03760000000000 1974-01-01 33.48140000000000 1975-01-01 32.17690000000000 1976-01-01 31.70730000000000 1977-01-01 31.90030000000000 1978-01-01 35.02500000000000 1979-01-01 38.00590000000000 1980-01-01 38.60010000000000 1981-01-01 37.86040000000000 1982-01-01 39.15900000000000 1983-01-01 41.32300000000000 1984-01-01 41.31940000000000 1985-01-01 40.43310000000000 1986-01-01 40.18260000000000 1987-01-01 39.86430000000000 1988-01-01 39.92300000000000 1989-01-01 41.26130000000000 1990-01-01 43.38660000000000 1991-01-01 43.63450000000000 1992-01-01 42.15550000000000 1993-01-01 41.06230000000000 1994-01-01 41.24950000000000 1995-01-01 53.04420000000000 1996-01-01 66.58710000000000 1997-01-01 71.18380000000000 1998-01-01 77.74240000000000 1999-01-01 86.08820000000000 2000-01-01 94.07400000000000 2001-01-01 70.54010000000000 2002-01-01 69.99290000000000 2003-01-01 78.24730000000000 2004-01-01 92.47140000000000 2005-01-01 110.46900000000000 2006-01-01 129.74700000000000 2007-01-01 147.17800000000000 2008-01-01 168.56200000000000 2009-01-01 174.03200000000000 2010-01-01 152.25600000000000 2011-01-01 123.52600000000001 2012-01-01 112.82799999999999 2013-01-01 106.48899999999999 2014-01-01 89.03540000000000 2015-01-01 56.84530000000000 2016-01-01 49.21580000000000