Year Percent 1990 3.18237 1991 3.23919 1992 3.11791 1993 2.99857 1994 2.9916 1995 2.97771 1996 2.97459 1997 2.86191 1998 2.76886 1999 2.72223 2000 2.56361 2001 2.48963 2002 2.37138 2003 2.35796 2004 2.34703 2005 2.0336 2006 1.94584 2007 1.89629 2008 1.87462 2009 1.80274 2010 1.77551 2011 1.88343 2012 1.97075 2013 2.14459 2014 1.99786 2015 2.06524 2016 1.92837 2017 1.97268 2018 1.94542 2019 1.9073 2020 2.00819 2021 1.90018 2022 1.82094