Year Number 2004-01-01 318 2005-01-01 323 2006-01-01 327 2007-01-01 326 2008-01-01 331 2009-01-01 337 2010-01-01 345 2011-01-01 344 2012-01-01 346 2013-01-01 339 2014-01-01 340 2015-01-01 346 2016-01-01 337