Year % 2005 4 2007 3.44 2008 3.15 2009 3.15 2011 3.13 2012 4.33 2013 4.8 2014 4.6 2015 5.3 2016 4.91 2017 16.81 2018 20.39 2019 12.61 2020 5.72 2021 6.25