user: Question: when was the site listed when the county is Cochise?
Columns: ['CERCLIS ID', 'Name', 'County', 'Proposed', 'Listed', 'Construction completed', 'Partially deleted', 'Deleted']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['AZD980695969', 'Abandoned Uranium Mines', 'Navajo Nation', '–', '–', '–', '–', '–']
SQL:

assistant: SELECT "Listed" FROM "Table" WHERE "County" = 'Cochise';