Write SQL query to solve given problem: What is the average number of terms served for a current legislator that's famous or impact?. Keep the solution inside sql tag ```sql [SQL-Query] ```
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