Extract from CIC website (calculation of physical stay in Canada before a PR can apply for the citizenship):
Time you have lived in Canada
"You must have been physically present in Canada as a permanent resident for at least 1,460 days during the six years immediately before the date of your application. You must also be physically present for at least 183 days during each of four calendar years that are fully or partially within the six years immediately before the date of application. These requirements do not apply to children under 18."
Hasan