A federal banking regulator said today that 90.6 percent of mortgages were current and performing at the end of the second quarter, compared with 90.2 percent at the end of the previous quarter and 88.7 percent a year earlier. Seriously delinquent mortgages, defined as those 60 or more days past due or held by bankrupt borrowers whose payments are 30 days or more past due, decreased to 3.8 percent, compared with 4 percent at the end of the previous quarter and 4.4 percent a year ago, the Office of the Comptroller of the Currency said in a news release. Foreclosures fell to their lowest level since 2008, when the OCC began compiling its mortgage report.