I should add that even though the conventional interest rate plummeted 4%+ from 1984 to 1989, it has now plummeted 6-7% BELOW the fixed rate of 1988-89 for the most “prime” borrowers.
I KNOW because I WAS ONE at that time who took out 11 7/8%, 10 1/8% and 9 3/4% fixed conventional mortgages from the late 70’s thru 1990 (all in SD, CA). At all times, I/we never had ANY MONTHLY DEBT on my/our “TRWs” but the mortgage on the family home. FICO scores did not exist back then, but I/we were considered “prime” borrowers.