The share of California homeowners late on their mortgage payments plunged to historic lows in the first quarter, according to a banking trade group.Across the state, only 1.82 percent of property owners were 30 days or more past due on their loans as of March 31 on a non-seasonally adjusted basis, the Mortgage Bankers Association found. That is the lowest default rate for California since at least 1979, and 0.31 percentage points lower than the default rate in the fourth quarter of 2004.