Year Number 1996 4.89130449295044 1998 6.52173900604248 2000 9.78260898590088 2002 10.8108110427856 2003 12.972972869873 2004 13.4328355789185 2005 12.7450981140137 2006 12.2549018859863 2007 15.5339803695679 2008 16.990291595459 2009 17.7033500671387 2010 18.6602878570557 2011 21.3270149230957 2012 24.1706161499023 2013 21.8009471893311 2014 17.7884616851807 2015 12.380952835083 2016 12.380952835083 2017 12.8571424484253 2018 11.9047622680664 2019 10 2020 10.4761905670166 2021 9.5238094329834 2022 9.90566062927246