The number of U.S. natural gas cargoes heading for European ports jumped by one-third over the weekend as the continent shivers amid a deepening energy crisis. There were 20 tankers bearing American gas heading for Europe, up from 15 on the day before the Christmas Eve holiday, according to data compiled by Bloomberg. Another 14 vessels were headed in the general direction of Europe while awaiting final orders. European gas prices dipped for a fourth straight session on expectations the U.S. deliveries will help ease supply concerns. Even after the recent slump, prices for the fuel are still 10 times higher than a year ago.