The average single-family home in San Francisco sold for 17% more in 2013 if it was marketed on the city’s MLS rather than if it were sold “off market,” according to a new report. The percentage narrows a bit for condos, which sold for 9% more on the MLS. The same report also found that despite this gap, 11% of S.F. sales occurred off-market in 2013. When looking at only the top 100 high-end properties, the percentage of off-market sales almost doubled, to 20%.