sentence: Prior to the main decline ( 2003 – 2006 ) , an average of 5.75 SQPx cases per year were submitted , compared with 73.50 cases per year during 2007 – 2008 and 3.00 cases per year during 2009 – 2012.Between March 2003 and October 2009 , 309 gray squirrel carcases were submitted , of which 52 % ( 160 ) underwent PCR analysis for SQPV , and of these , 27 % ( 43 of 160 ) were positive .