-- Database schema
| coins : id [ INTEGER ] primary_key , name [ TEXT ] , slug [ TEXT ] , symbol [ TEXT ] , status [ TEXT ] , category [ TEXT ] , description [ TEXT ] , subreddit [ TEXT ] , notice [ TEXT ] , tags [ TEXT ] , tag_names [ TEXT ] , website [ TEXT ] , platform_id [ INTEGER ] , date_added [ TEXT ] , date_launched [ TEXT ] | historical : date [ DATE ] , coin_id [ INTEGER ] , cmc_rank [ INTEGER ] , market_cap [ REAL ] , price [ REAL ] , open [ REAL ] , high [ REAL ] , low [ REAL ] , close [ REAL ] , time_high [ TEXT ] , time_low [ TEXT ] , volume_24h [ REAL ] , percent_change_1h [ REAL ] , percent_change_24h [ REAL ] , percent_change_7d [ REAL ] , circulating_supply [ REAL ] , total_supply [ REAL ] , max_supply [ REAL ] , num_market_pairs [ INTEGER ] |
-- -- What is the average monthly circulating supply for Frozen in 2014.

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';