Year Percent change 1999 8.432 2000 12.418 2001 12.468 2002 11.703 2003 12.986 2004 13.695 2005 13.567 2006 13.307 2007 12.5 2008 7.558 2009 4.385 2010 5.247 2011 5.471 2012 6.486 2013 7.899 2014 8.2 2015 7.473 2016 5.151 2017 6.334 2018 6.689 2019 6.448 2020 6.593 2021 6.732 2022 6.868 2023 6.934 2024 6.956