Customers swarmed to the nation’s post offices in December and deposited 1.45 trillion yen more than they withdrew, apparently underlining the public’s disappointment in the record low interest rates at other financial institutions. The figure was announced Jan. 8 by the Posts and Telecommunications Ministry.Of the net growth, Tsuujo ordinary postal savings accounted for 1.28 trillion yen, a record one-month mark. Ordinary postal savings deposits, which can be drawn on at any time, carry an annual after-tax interest of just 0.2 percent. Still, it is much better than the 0.08 percent offered at most banks.The ministry said the balance of all postal savings came to 222.42 trillion yen, up 1 percent from a month earlier. Because of the sheer size, Japanese postal savings have often been referred to as “the world’s biggest bank.” The Teigaku fixed-amount deposits climbed by 192.2 billion yen in December.A ministry official said the brisk rise in ordinary savings showed customers’ continuing preference for flexible savings rather than fixed deposits. “The balance of postal savings increased because withdrawals for payment for durable goods through November took a break,” the official said.