Year % 2005 12.7946976817766 2006 12.1287142857308 2007 11.9967024250431 2008 11.6003318847199 2009 10.8398139038407 2010 11.5482423769556 2011 11.212614187492 2012 10.424496236502 2013 9.80449529945923 2014 10.0271381339535 2015 10.1660266444292 2016 11.449679519721 2017 12.4809787364152 2018 12.4873666379903 2019 12.7099958279281 2020 11.8046716942433 2021 12.1533932149137 2022 11.7829272809896