Year Number 1999 15.59241 2000 15.25432 2001 15.05386 2002 15.049 2003 14.90022 2004 14.55741 2005 14.1753 2006 14.361 2007 14.46225 2008 13.0991 2009 13.45208 2010 13.80075 2011 13.97348 2012 15.09369