Write SQL query to solve given problem: What was the number of Bitcoins verifiably burned until 2013/4/28?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T2.max_supply - T2.total_supply FROM coins AS T1 INNER JOIN historical AS T2 ON T1.id = T2.coin_id WHERE T2.date = '2013-04-28' AND T1.name = 'Bitcoin'