Further signs of an economic problem — American consumers hit the brakes in December with credit card debt. During December, U.S. cardholders added a meager $2.0 billion in total revolving debt compared $6.0 billion for December 1999. The dramatic slowdown in revolving debt, which is 95% credit card debt, hit during the critical holiday shopping season. During November and December 2000, consumers racked up $8.0 billion in new card debt compared to $11.5 billion for the same period last year, according to preliminary data released last week by the Federal Reserve. Since the beginning of this year, American consumers have increased total revolving consumer debt by $67 billion. Overall, consumer revolving credit is now growing at a 3.6% rate compared to 12.5% for December 99, according to the Federal Reserve Board. At the end of December, American consumers were $1.525 trillion in debt, exclusive of home mortgages. Overall consumer credit is growing at an annual rate of 2.4% based on the December data.