user: Question: What was the vacancy date for Thomas Thomasberg?
Columns: ['Team', 'Outgoing manager', 'Manner of departure', 'Date of vacancy', 'Replaced by', 'Date of appointment', 'Position in table']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Aarhus GF', 'Erik Rasmussen', 'Sacked', '20 May 2010', 'Peter Sørensen', '1 July 2010', 'Pre-Season']
SQL:

assistant: SELECT "Date of vacancy" FROM "Table" WHERE "Outgoing manager" = 'Thomas Thomasberg';