What is the average attendance of meetings in 2020?
meetings in 2020 refers to type = 'Meeting' where YEAR(event_date) = 2020; average = DIVIDE(COUNT(event_id), COUNT(DISTINCT event_name))
SELECT CAST(COUNT(T2.link_to_event) AS REAL) / COUNT(DISTINCT T2.link_to_event) FROM event AS T1 INNER JOIN attendance AS T2 ON T1.event_id = T2.link_to_event WHERE SUBSTR(T1.event_date, 1, 4) = '2020' AND T1.type = 'Meeting'