Letter from the Secretary of the Treasury, transmitting the information required by the resolution of the House of Representatives of the 19th February last, in relation to exports of domestic and foreign produce from 1791 to 1837; the value of imports from 1821 to 1837; the value of imports free of duty and dutiable during the same period; and of the duties which accrued, and drawbacks paid, from 1791 to 1836.