Year Percent 1990 11.281 1991 11.617 1992 11.988 1993 12.322 1994 12.664 1995 13.021 1996 13.086 1997 13.157 1998 13.231 1999 13.313 2000 13.41 2001 12.973 2002 13.625 2003 12.567 2004 12.728 2005 12.894 2006 13.281 2007 16.066 2008 15.656 2009 16.48 2010 16.264 2011 16.206 2012 15.79 2013 14.768 2014 14.777 2015 14.809 2016 14.815 2017 14.886 2018 14.954 2019 15.018 2020 15.078 2021 15.134 2022 15.185 2023 15.233 2024 15.28 2025 15.326 2026 15.38 2027 15.435 2028 15.493 2029 15.56 2030 15.638