Zillow and Trulia are not capable to sifting data, they are essentially worthless as are almost all automated valuation models (AVMs). To accurately gauge anything you need filtered information that relates to your specific area.
Drop me line, I can tap my appraisal resources and pull statisical data using SMART in about 5 minutes.
Hank Miller, SRA, ABR
Associate Broker & Certified Appraiser
Prudential GA Realty