Year | Peak month | Trough month |
---|---|---|
2004 | July | October |
2005 | June | October |
2006 | June | November |
2007 | July | September |
2008 | July | September |
2009 | June | November |
2010 | April | December |
2011 | May/September | January |
2012 | February | November |
2013 | July | December |
2014 | August | December |