Year % 2008 2.96443634829966 2009 3.65846380276455 2010 3.88993974941601 2011 3.89022617345404 2012 4.26650883747211 2013 4.53258062385818 2014 4.2366463637383 2015 4.67838137015214 2016 5.15137252858059 2017 5.37401395271466 2018 5.41296527913727 2019 5.4018377559901 2020 5.3043701499748 2021 5.26284521874151