Don't look for the housing market to peak anytime soon.  According to a new study by TransUnion, an estimated 17 million first-time homebuyers will enter the housing market over the next five years. The study found consumers who are 39 years old or younger represent a growing majority of homebuyers, capturing 60% of the total home buying market at the end of last year. Joe Mellman, vice president at TransUnion, also discussed how trended data -- a more analytical look at consumer credit behavior -- can help in the mortgage underwriting process.