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