Year % 2001 13.229878914820805 2002 12.74888263295918 2003 12.247103081177853 2004 12.791599200752765 2005 13.117818105992043 2006 13.681958215526555 2007 14.225638906814316 2008 11.520196882399194 2009 14.868474432949508 2010 14.99558099961521 2011 14.279894558523093 2012 14.927662912601669 2013 15.08394839046368 2014 13.861866611187276 2015 16.987406807583838 2016 18.051082483449633 2017 17.367245574852493 2018 16.61037048648688 2019 15.648496568825582 2020 18.20219728060369 2021 18.681162595132736 2022 17.362883666467607 2023 18.25042991857294