user: Question: How many weeks featured Duffy as the original artist?
Columns: ['Week #', 'Theme', 'Song choice', 'Original artist', 'Order #', 'Result']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Audition', 'N/A', '" Big Girls Don\'t Cry "', 'Fergie', 'N/A', 'Advanced']
SQL:

assistant: SELECT COUNT("Theme") FROM "Table" WHERE "Original artist" = 'Duffy';