Data from the National Council of Real Estate Investment Fiduciaries shows that net operating income (used in conjunction with cap rates to value properties) among privately held real estate grew the most in the apartment sector last year. Apartment NOI grew 6.1% during the year, followed by 3.3% for office, 2.9% for retail and 2.2% industrial properties. The overall NCREIF Property index had NOI growth of 3.72%, outpacing the rate of inflation by 196 basis points.