Year Number 1995 16100000 1996 19085000 1997 23660000 1998 25499000 1999 29215000 2000 37226000 2001 40129000 2002 41737000 2003 42857000 2004 44974000 2005 45762000 2006 47733000 2007 52271000 2008 51336000 2009 47573000 2010 49006000 2011 49969000 2012 47185000 2013 48345000 2014 51168000 2015 55858000 2016 57587000 2017 59238000 2018 57668000 2019 60021000 2020 21608000