Year Percent 1987-01-01 0.2235266 1988-01-01 0.2416589 1989-01-01 0.3208047 1990-01-01 0.2713295 1991-01-01 0.4541344 2002-01-01 1.9665010 2003-01-01 1.9843000 2004-01-01 2.4394140 2005-01-01 2.7760610 2006-01-01 3.1183180 2007-01-01 3.1868390 2008-01-01 2.2489450 2009-01-01 3.1280880 2010-01-01 3.0583450