There has been little question that this year’s rising interest rate environment has produced a surge in adjustable-rate mortgage lending – particularly loans involving hybrid products. But just how big the ARM market in 2004 has been open to debate. According to first half numbers compiled by Inside Mortgage Finance, the ARM share of total origination climbed to a record-shattering 55.2 percent in the first six months of the year as an estimated $765 billion in…