user: Question: WHAT IS THE AVERAGE DATE OF RELEASE FOR Thickskin?
Columns: ['Date of release', 'Title', 'Label', 'Oricon peak', 'RIAA cert.']
Types: ['real', 'text', 'text', 'real', 'text']
Sample row: [1989.0, 'Skid Row', 'Atlantic', 5.0, '5x platinum']
SQL:

assistant: SELECT AVG("Date of release") FROM "Table" WHERE "Title" = 'Thickskin';