Show the average amount of transactions for different investors.
SELECT investor_id ,  avg(amount_of_transaction) FROM TRANSACTIONS GROUP BY investor_id
SELECT investor_id ,  avg(amount_of_transaction) FROM TRANSACTIONS GROUP BY investor_id
[{'investor_id': 2, 'avg(amount_of_transaction)': 24403.6612}, {'investor_id': 3, 'avg(amount_of_transaction)': 61.06666666666666}, {'investor_id': 6, 'avg(amount_of_transaction)': 302507.6996}, {'investor_id': 7, 'avg(amount_of_transaction)': 822.803}, {'investor_id': 8, 'avg(amount_of_transaction)': 0.0}, {'investor_id': 14, 'avg(amount_of_transaction)': 4.5263}, {'investor_id': 17, 'avg(amount_of_transaction)': 78035671.4424}, {'investor_id': 18, 'avg(amount_of_transaction)': 14.1285}, {'investor_id': 19, 'avg(amount_of_transaction)': 103742065.5898}, {'investor_id': 20, 'avg(amount_of_transaction)': 82057.207}]