WASHINGTON (AP) — The number of Americans applying for mortgages has fallen 63 percent since a May peak, reflecting a cooling housing market and higher borrowing rates.The Mortgage Bankers Association says applications fell a seasonally adjusted 6.3 percent last week from a week earlier. Applications are now at a 13-year low.The drop-off follows a 1 percentage point increase in mortgage rates from historic lows last spring. The average for a 30-year mortgage is 4.47 percent, according to mortgage buyer Freddie Mac.Home sales stalled and began to fall once rates steadily increased after May.