You can request your travel history here:
http://www.cbsa-asfc.gc.ca/agency-agence/reports-rapports/pia-efvp/atip-aiprp/thr-rav-eng.html
Note that although it says you don't need to request is for a citizenship application, there is nothing wrong with doing so if it helps you to fill out the calculator.
Note that this report will include all entries into Canada, no matter if from the US or at an airport. It will also include all exits, but only for those cases where you crossed the LAND border to the US.