You've mixed up inflation rate with mortgage interest rates. In the 70s the inflation rate was consistently over 8%. For 10 years, from 1973 to 1982, Canada's annual inflation rate averaged 9.62%. And for 9 more years after that (83-91) inflation was running just under 5% annually. Everything nearly quadrupled in price in 19 years between 1973 and 1991.
Mortgage rates were also pretty high over that entire period but they really took off in the early 80s when central banks jacked rates to wrestle inflation down.
Mortgage rates are still low compared to the 70s and 80s and even the 90s (although I recall when mortgage rates dropped into the single digits in the early 90s - like 9% or something - and everyone was saying "we should buy a house!"). For 20 years in the 70s and 80s, 5-year mortgage rates averaged >12%.
The problem is that housing prices kind of rise in lockstep with payments. This chart shows that in Canada, the mortgage payment to median income ratio fluctuates between 30% and 50% with occasional spikes when interest rates suddenly rise. Certain markets (Toronto, Vancouver) are far worse. Winnipeg's not on here but probably compares closely with Montreal.
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