Year % 2008 7.8723935463483 2009 9.09665946603969 2010 9.1132626860378 2011 8.02868558600608 2012 8.46235298163152 2013 7.91002963151823 2014 7.89299433510758 2015 8.33527954047096 2016 8.52734577902533 2017 8.37412119960357 2018 8.04086712352321 2019 8.23996458301581