Iowa credit-card holders are holding down their debt load better than the national average. Robert McKinley is with “cardweb-dot-com,” a company that offers cards, tracks their features and compiles data on our use of credit.He says Iowans have an average of 39-hundred dollars in debt, compared with 54-hundred nationally. By contrast, Nebraska’s average is higher than the national.He says East- and west coast states use plastic more, reflecting higher cost of living, though those more “progressive” states also see more bankruptcy. McKinley says an interesting thing happened in 2001.Consumers began to “downshift,” from recent growth rates of 10-15 percent a year in credit-card usage, last year it was just nine percent growth.It changed after September eleventh, and in the fourth quarter consumers began to pay down debt.