Results of the study, which was conducted by three leading industry consultants, show that the value of apartment stock has increased an average of 5.5% every year since 1990. One of the benefits of the research, explains NMHC Chief Economist Mark Obrinsky, is that it "allows the industry to flex its political muscle by showing its size and value."

Not surprisingly, the study shows that New York City tops the apartment-unit value list, with a total valuation of nearly $227 billion. The city's 1.8 million units carry an averaging rent of $150/sf. However, judging by value per sf alone, the northern California city of San Jose leads the country with an average $301.50 per sf.