CREATE TABLE table_24911 ("College" TEXT, "2007 Headcount" FLOAT, "2007-2008 credit hours" FLOAT, "County population 18 yrs+" FLOAT, "Penetration in terms of Enrollment per 1000 adults" FLOAT, "In-county tuition per credit hour  ( fall 2009 ) " TEXT)

What is the biggest number for county population 18 years+?
SELECT MAX("County population 18 yrs+") FROM table_24911
SELECT MAX("County population 18 yrs+") FROM "table_24911"