those for mortgages and other loans - were so high in 1990, so that the divergence between these two lines is greatest at that time, reflects two factors. First, personal loans were a much larger share of total household debt at that time than they are now.
Second, the average rate of interest on personal loans is usually higher than for mortgages, and they rose much more in the late 1980s than did mortgage rates. Both these series represent averages across the household sector. But experience differs markedly between households.