Year U.S.=100 1970-01-01 36.82854407 1971-01-01 36.97209909 1972-01-01 38.09335394 1973-01-01 36.05328878 1974-01-01 34.06640792 1975-01-01 40.98763206 1976-01-01 45.25588203 1977-01-01 46.19230542 1978-01-01 46.63997354 1979-01-01 43.55132620 1980-01-01 41.65358327 1981-01-01 44.84150745 1982-01-01 44.66216551 1983-01-01 39.67077444 1984-01-01 37.26991395 1985-01-01 41.83441543 1986-01-01 40.38689630 1987-01-01 36.92669538 1988-01-01 38.25635381 1989-01-01 36.80303874 1990-01-01 27.12067527 1991-01-01 30.04213005 1992-01-01 28.55044760 1993-01-01 22.50276058 1994-01-01 21.92316801 1995-01-01 21.93185058 1996-01-01 23.54300048 1997-01-01 25.97128941 1998-01-01 26.07697932 1999-01-01 19.12474041 2000-01-01 17.86102023 2001-01-01 17.92869753 2002-01-01 19.61403419 2003-01-01 20.90019251 2004-01-01 21.19225273 2005-01-01 24.22069822 2006-01-01 24.37346236 2007-01-01 26.07733776 2008-01-01 27.56169877 2009-01-01 28.07752964 2010-01-01 27.55518153