"Because Canadian Immigration figures have increased every decade over the past 150 years. " 

That's just not true. Historically, immigration levels have tended to fluctuate wildly, usually influenced by economic factors like the post-WWII economic boom but also by external factors like the inflow of Hungarian refugees in the mid-1950s. Only since Mulroney's regime, however, have continuously high immigration levels been sustained despite the country undergoing at least two serious recessions during this period. Further, immigration in an agrarian nation, where employed to settle vast expanses of underpopulated territory, as was the case in the west in the decade prior to WWI, is a substantially different enterprise than is immigration in a mainly urban post-industrial society. It has to be noted that the percentage of foreign-born residents living in Canada has in the current decade reached the highest level since the pre-WWI era.