WASHINGTON (AP) _ Sales of existing homes soared 13.5 percent in 1998 to 4.78 million, riding low mortgage rates and American prosperity to the best year on record.

Sales easily surpassed the previous record, 4.21 million, set the previous year, the National Association of Realtors said today. The group began tracking sales in 1968.

In December, sales rose 3.1 percent from the month before to a seasonally adjusted annual rate of 5.03 million, also a record.

Strong buying demand pushed the inventory of homes for sale, 1.58 million, to a record low level _ a 3.8 month supply at the December sales rate.