The U.S. home vacancy rate fell to its lowest level since 2006 as housing demand improved and foreclosures slowed, according to a new Census Bureau report. The vacancy rate declined from 2.2% in the previous quarter to 2.1%, while the homeownership rate rose slightly. Available housing inventory is decreasing as investors purchase more discounted foreclosures and distressed properties. Mortgage rates also edged up after hitting record lows in recent weeks.