user: Question: With a previous number of 68165, what is the oldest converted date?
Columns: ['Number', 'Previous Number(s)', 'Previous Class', 'Converted', 'Withdrawn', 'Disposal']
Types: ['text', 'real', 'text', 'real', 'real', 'text']
Sample row: ['1', 68845.0, 'J52', 1952.0, 1958.0, 'Scrapped (1958)']
SQL:

assistant: SELECT MIN("Converted") FROM "Table" WHERE "Previous Number(s)" = 68165.0;