-- month in the last year had the highest average IACV for closed won deals?

SELECT
  date_trunc('month', close_date)::date   AS month,
  AVG(weighted_iacv)                      AS iacv
  FROM sdfc_opportunity_xf
  WHERE (is_closed AND is_won AND close_date BETWEEN '2018-08-14' and '2019-08-14')
  GROUP BY month
  ORDER BY iavc
  LIMIT 1