Travel between your country of residence and your country of origin does not need to be reported.
It is incorrect that the idea of the travel history is to "explain" each stamp in your passport. CIC does not even want to see the stamps in your passport (the bio page is enough) and does not require your old passports. The stamps are helpful of course in retracing your travel history so you don't forget anything.
For example, many European countries do not stamp the passport once you are in the Schengen-zone, but you still need to report travel to individual countries even if you don't have a stamp. Some other countries no longer stamp passports but use an electronic system to keep track of entry and exit.
So in other words, follow the instructions. Report all international trips outside your country of residence or origin, whether you have a stamp for it or not.