Year Percent 1984-01-01 39.964600000000000 1985-01-01 42.878000000000000 1986-01-01 50.351000000000006 1987-01-01 51.801100000000000 1988-01-01 58.034700000000000 1989-01-01 59.627200000000000 1990-01-01 60.623900000000000 1991-01-01 60.670800000000000 1992-01-01 55.846800000000000 1993-01-01 53.656700000000000 1994-01-01 51.009100000000000 1995-01-01 52.479200000000000 1996-01-01 51.210800000000000 1997-01-01 46.662000000000000 1998-01-01 47.288600000000000 1999-01-01 44.132200000000000 2000-01-01 43.698900000000000 2001-01-01 44.211000000000006 2002-01-01 48.059300000000000 2003-01-01 54.176500000000000 2004-01-01 59.885400000000000 2005-01-01 63.551700000000000 2006-01-01 65.226200000000000 2007-01-01 64.641800000000000 2008-01-01 66.377000000000000 2009-01-01 74.348300000000000 2010-01-01 80.628400000000000 2011-01-01 74.176100000000000 2012-01-01 70.837200000000000 2013-01-01 74.034100000000000 2014-01-01 71.264900000000000 2015-01-01 72.962700000000000 2016-01-01 77.687200000000000