Year Number 2006 4362000 2007 3627000 2008 3847000 2009 3639000 2010 4311000 2011 4020000 2012 4108000 2013 4228000 2014 4292000 2015 3981000 2016 4143000 2017 4294000 2018 4702000 2019 4881000 2020 1643000