http://www.cic.gc.ca/english/information/applications/guides/5445ETOC.asp#appendixA
Appendix A: Residency obligation
Minimum residency obligations
You must meet the residency obligation to obtain a Permanent Resident Card.
If you have been a permanent resident for Five (5) years or more
you must have been physically present in Canada for a minimum of 730 days within the past five (5) years.
If you have been a permanent resident for less than five (5) years
you must show that you will be able to meet the minimum of 730 days physical presence in Canada at the five (5)-year mark.