CREATE TABLE table_20237 ("Date" TEXT, "Cover model" TEXT, "Centerfold model" TEXT, "Interview subject" TEXT, "20 Questions" TEXT, "Pictorials" TEXT)

How many total interview subjects wererthere when the centerfold model was Tamara Witmer?
SELECT COUNT("Interview subject") FROM table_20237 WHERE "Centerfold model" = 'Tamara Witmer'
SELECT COUNT("Interview subject") FROM "table_20237" WHERE "Centerfold model" = 'Tamara Witmer'