Property search and valuation site Zillow has expanded its property database and improved the accuracy of its "Zestimate" home valuations, the site announced today. Zillow has added more than 25 million new Zestimates to its database, bringing its coverage total to about 100 million homes, or more than three-quarters of all homes in the country, the site said. A new algorithm takes into account user-submitted informationĀ not found in public recordsĀ on more than 28 million properties, such as remodeling updates or other property details. The algorithm has improved Zillow's median margin of error to 8.5 percent nationwide from a previous error margin of 12.3 percent, the site said. The margin of error is calculated by comparing Zestimates to actual sale prices.Zestimate accurac...