The biggest component of CPI is housing/shelter. The housing component does not measure the costs of purchasing a home; it measures the expense of renting a home. Even if you are a home owner it values your housing expense as the cost to rent a comprable home. It is my understanding that this was changed after the skyrocketing interest rates in the 80s and because homes are purchased for rental investments.
I don't know about your area, but here in CA home prices have skyrocketed and home rents have dropped significantly. Sounds like a bogus statistic in order to keep foreign capital flowing into our markets.