Year Percent 1973-01-01 33.166800000000000 1974-01-01 34.056500000000000 1975-01-01 37.914700000000000 1976-01-01 37.821000000000000 1977-01-01 38.887200000000000 1978-01-01 41.249900000000000 1979-01-01 51.460300000000000 1980-01-01 34.678800000000000 1981-01-01 36.316000000000000 1982-01-01 39.773500000000000 1983-01-01 41.866900000000000 1984-01-01 37.727300000000000 1985-01-01 34.624100000000000 1986-01-01 28.382200000000000 1987-01-01 24.851600000000000 1988-01-01 36.938700000000000 1989-01-01 55.100800000000000 1990-01-01 44.875600000000000 1991-01-01 29.914100000000000 1992-01-01 35.908400000000000 1993-01-01 45.826100000000000 1994-01-01 50.010000000000000 1995-01-01 47.397200000000000 1996-01-01 51.090600000000000 1997-01-01 54.900100000000000 1998-01-01 55.946300000000000 1999-01-01 57.608999999999995 2000-01-01 61.898300000000000 2001-01-01 61.764100000000000 2002-01-01 57.969300000000000 2003-01-01 60.062400000000000 2004-01-01 61.062100000000000 2005-01-01 64.971300000000000 2006-01-01 69.505600000000000 2007-01-01 73.041900000000000 2008-01-01 75.817800000000000 2009-01-01 80.278200000000000 2010-01-01 80.514300000000000 2011-01-01 87.025500000000000 2012-01-01 92.650700000000000 2013-01-01 94.646900000000000 2014-01-01 95.846000000000000 2015-01-01 102.325000000000000 2016-01-01 105.751000000000000