What is the average number of terms served for a current legislator that's famous or impact?
average = DIVIDE(COUNT(bioguide), COUNT(bioguide_id)); legislator that's famous or impact refers to wikipedia_id is not null;
SELECT CAST(COUNT(T2.bioguide) AS REAL) / COUNT(DISTINCT T1.bioguide_id) FROM current AS T1 INNER JOIN `current-terms` AS T2 ON T1.bioguide_id = T2.bioguide WHERE T1.wikipedia_id IS NOT NULL