Cook County lost more people between 2000 and 2005 than any county in the nation, according to Census Bureau estimates released Thursday that also show continued gains in suburban and exurban counties across the region and portions of the nation. The new figures--based on administrative records and estimates for births, deaths and net migration--show the county lost more than 73,000 people, or 1.4 percent, since the last official count in April 2000. The largest-loser designation can partly be attributed to Cook County's massive size, because raw numbers were used for the rankings. Still, among the nation's 10 largest counties, Cook,...