+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
I agree. I was also going from what the previous version of the form said - i.e., 'whichever period is longer.'

Forum member Nester in this thread reported that the visa officer requested him to redo the form with info from the age of 18, when he had originally only included info from the last 10 years:
http://www.canadavisa.com/canada-immigration-discussion-board/i-am-confused-please-help-t80794.15.html
 
Thats a good suggestion Aneyshar, thank you. I will definitely put in an attachment like you suggested so that I would not be held account for if there is mistakes in the year and month