Year Percent 1960-01-01 13.5000 1961-01-01 12.5950 1962-01-01 12.8700 1963-01-01 13.5200 1964-01-01 14.2750 1965-01-01 14.4200 1966-01-01 15.6900 1967-01-01 15.4450 1968-01-01 15.6350 1969-01-01 15.2300 1970-01-01 16.2100 1971-01-01 16.2200 1972-01-01 17.8900 1973-01-01 18.9400 1974-01-01 18.2950 1975-01-01 20.4000 1976-01-01 21.5550 1977-01-01 22.6850 1978-01-01 23.2100 1979-01-01 23.5750 1980-01-01 23.6059 1981-01-01 24.9200 1982-01-01 25.4050 1983-01-01 27.2850 1984-01-01 27.8400 1985-01-01 27.1400 1986-01-01 27.4100 1987-01-01 27.6000 1988-01-01 26.8000 1989-01-01 28.5450 1990-01-01 25.5400 1991-01-01 28.3500 1992-01-01 26.8850 1993-01-01 28.2700 1994-01-01 25.5900 1995-01-01 26.1300 1996-01-01 28.0000 1997-01-01 28.5400 1998-01-01 30.0350 1999-01-01 31.7100 2000-01-01 32.5600 2001-01-01 34.1200 2002-01-01 33.5000 2003-01-01 34.8900 2004-01-01 35.5550 2005-01-01 35.3000 2006-01-01 34.9600 2007-01-01 37.2250 2008-01-01 38.6600 2009-01-01 42.6800 2010-01-01 41.7700 2011-01-01 42.0400 2012-01-01 42.9700 2013-01-01 44.5900 2014-01-01 47.6600 2015-01-01 49.5400