Year Percent 2003 0.92403 2004 0.92619 2006 0.93542 2007 0.92409 2008 0.90633 2009 0.92123 2010 0.88459 2011 0.89291 2012 0.91258 2014 0.87104 2015 0.85031 2016 0.84751