Originations of home-equity loans jumped 12.2 percent last year, paced by heavy production of revolving lines of credit and the growing piggyback second mortgage business, according to a new analysis by Inside Mortgage Finance. An estimated $359 billion of home-equity loans were originated in 2005, representing about 11.5 percent of total production. The biggest chunk of that volume came from new home-equity line of credit originations by banks, thrifts and other portfolio lenders, estimated at… [One data table included]