 However, in the United States, the average interest rates for fixed-rate mortgages in the housing market started in the tens and twenties in the 1980s and have (as of 2004) reached about 6 per cent per annum.However, gross borrowing costs are substantially higher than the nominal interest rate and amounted for the last 30 years to 10.46 per cent.In Denmark, similar to the United States mortgage market, interest rates have fallen to 6 per cent per annum.