user: Question: How many cover models were on the edition that featured Jennifer Pershing as the centerfold?
Columns: ['Date', 'Cover model', 'Centerfold model', 'Interview subject', '20 Questions', 'Pictorials']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1-09', 'Carmen Electra', 'Dasha Astafieva', 'Richard Branson', 'Marston and Cooper Hefner', 'Carmen Electra']
SQL:

assistant: SELECT COUNT("Cover model") FROM "Table" WHERE "Centerfold model" = 'Jennifer Pershing';