Database: coinmarketcap
Question: What is the average monthly circulating supply for Frozen in 2014.
SQL: SELECT CAST(SUM(T2.circulating_supply) AS REAL) / 12 FROM coins AS T1 INNER JOIN historical AS T2 ON T1.id = T2.coin_id WHERE T1.name = 'Frozen' AND STRFTIME('%Y', T2.date) = '2014'