Write SQL query to solve given problem: In how many papers and in what years was the International Conference on Database Theory published?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(T1.Id) AS PAPER, COUNT(DISTINCT T1.Year) AS YEARS FROM Paper AS T1 INNER JOIN Conference AS T2 ON T1.ConferenceId = T2.Id WHERE year != 0 AND T2.FullName = 'International Conference on Database Theory'