Year Number of 2000 24000 2001 24000 2002 18000 2003 15000 2004 16000 2005 18000 2006 18000 2007 19000 2008 19000 2009 18000 2010 18000 2011 18000 2012 19000 2013 18000 2014 18000 2015 18000 2016 17000 2017 18000 2018 18000 2019 15000 2020 15000