PORTLAND, Ore. – Advocates of credit unions issuing credit cards will frequently point out that credit cards can be key to strengthening the credit union's relationship with its members and to cross selling other products. But while that may be true, it's also true that credit cards can remain among the more challenging assets credit unions can manage. These three graphs and two charts from credit union card portfolio broker Asset Exchange, Portland, Ore., illustrate that reality. As the number of credit union members has grown, the percentage of them that hold their credit union's credit card has dropped since credit cards are not usually the first credit union product new members acquire. Meanwhile, the percentage of credit union assets that credit cards represent have leveled off after dropping since 2000, standing now at roughly 4.1% and a rising number of credit unions have begun to make their credit card portfolios grow. However, the two charts point out that mere growth in outstanding balances, whether measured per account or per member, is no guarantee of overall credit union profitability.