U.S. households increased their borrowing by the most since 2008 in the second quarter of the year, while their worth declined, the Federal Reserve (Fed) said Thursday. According to Fed data, household debt rose $39.4 billion, the first gain in more than a year, to $13 trillion in the second quarter of 2012. It was just $2 trillion shy of the United States total yearly economic output. Americans financial net worth fell by more than $300 billion to $62.7 trillion, the Fed said.