Current legislator Roger F. Wicker has not been a representative for how many terms?
Roger F. Wicker is an official_full_name; not a representative refers to district IS NULL OR district = ''
SELECT SUM(CASE WHEN T1.official_full_name = 'Roger F. Wicker' THEN 1 ELSE 0 END) AS count FROM current AS T1 INNER JOIN `current-terms` AS T2 ON T1.bioguide_id = T2.bioguide WHERE T2.district IS NULL OR T2.district = ''