Year Number 2007 12709000 2008 13042000 2009 13754000 2010 14254000 2011 15944000 2012 14916000 2013 13434000 2014 13952000 2015 17625000 2016 18277000 2017 20274000 2018 22287000 2019 22816000 2020 6236000