How can CIC know my exact residence time in Canada

[nando2011]

When a canadian permanent resident cross the land border by airplane to European Community, they do not stamp the passport, and as far as I remember they do not even check/scan PR card.
So how can I remember all my departures from Canada if I was traveling quite a bit within the last 5 years (years of my PR card validity)?

Also how can we (me and CIC) check how many days I was residing in Canada?

I was living in Canada for more then 1.5 year without leaving the country. However before that i travelled in and out a lot. I had only entrance stamps in my passport. And, actually, that passport I had to change due to expired validity date. Now I have a new passport without any stamps.
I would like to apply for the renewal of my canadian PR. I do not want to lie but I am afraid I cannot provide the exact number of days which I was residing/living in Canada. What should I do?

 

[scylla]

Do your best to try to remember your travel dates. (Maybe you still have some of your itineraries saved in emails?) Going forward, keep track of your travel in a spreadsheet.

CIC has access to airline manifests.

 

[Alabaman]

CIC has access to airline manifests.

How do you know this??

 

[internee]

You can request the same from Canada Border and Customs Agency in Otawa for your travel record in Canada. It will provide you all your entries on Canadian border through air transport.