Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the biggest number for county population 18 years+?

### Inputs:
table_name: table, columns: ['College', '2007 Headcount', '2007-2008 credit hours', 'County population 18 yrs+', 'Penetration in terms of Enrollment per 1000 adults', 'In-county tuition per credit hour (fall 2009)']

### Response:
SELECT MAX County population 18 yrs+ FROM table