Year Percent 1980-01-01 3.2275200000000000 1981-01-01 3.4680000000000000 1982-01-01 3.6011900000000003 1983-01-01 3.4631800000000004 1984-01-01 4.1192000000000000 1985-01-01 4.8555900000000000 1986-01-01 6.0766900000000000 1987-01-01 9.1567100000000000 1988-01-01 9.5692899999999990 1989-01-01 10.6319000000000000 1990-01-01 13.6224000000000000 1991-01-01 16.2140000000000020 1992-01-01 17.6495000000000000 1993-01-01 17.3659000000000000 1994-01-01 15.1280000000000000 1995-01-01 10.2425000000000000 1996-01-01 10.3980000000000000 1997-01-01 12.8111000000000000 1998-01-01 10.9116000000000000 1999-01-01 11.2854000000000000 2000-01-01 12.5772000000000000 2001-01-01 12.7672000000000000 2002-01-01 14.4771000000000000 2003-01-01 16.2408000000000000 2004-01-01 18.6827000000000000 2005-01-01 18.0808000000000000 2006-01-01 22.6171000000000000 2007-01-01 21.0588000000000000 2008-01-01 19.8807000000000000 2009-01-01 30.6917000000000000 2010-01-01 31.9569999999999970 2011-01-01 29.8242000000000000 2012-01-01 38.2810000000000000 2013-01-01 42.8483000000000000 2014-01-01 40.6370000000000000 2015-01-01 49.8151000000000000 2016-01-01 51.0706000000000000