instruction: Percent of users whose first post was a question of score > 0, out of all users who have posted.
response: WITH QA AS (SELECT *, ROW_NUMBER() OVER (PARTITION BY OwnerUserId ORDER BY OwnerUserId, CreationDate) AS PostOrder FROM Posts WHERE PostTypeId IN (1, 2) AND CommunityOwnedDate IS NULL AND DeletionDate IS NULL) SELECT ROUND(100.0 * num.NFirstGoodQ / denom.NPosters, 2) FROM (SELECT COUNT(Id) AS NPosters FROM Users WHERE Id IN (SELECT DISTINCT OwnerUserId FROM QA)) AS denom JOIN LATERAL (SELECT COUNT(DISTINCT OwnerUserId) AS NFirstGoodQ FROM QA WHERE PostOrder = 1 AND PostTypeId = 2 AND Score > 0) AS num