Year % 1997 3.9198606271777012 1998 3.4936138241923373 1999 3.8791495710555743 2000 3.881700554528649 2001 3.99556048834628 2002 5.678466076696166 2003 6.014434643143546 2004 6.957217113154747 2005 6.40907697025453 2006 8.632425742574267 2007 8.849009900990108 2008 8.767038413878574 2009 9.085347200978898 2010 10.98317094774136 2011 10.508701472556886 2012 14.167433302667888 2013 16.420064958498735 2014 16.75108538350217 2015 16.901918204849792 2016 17.567159674011474 2017 16.581402347276573 2018 16.937424789410368 2019 16.26865671641793 2020 18.432076600837842 2021 17.021933889403766 2022 17.27781230577998 2023 16.608447126071763