My understanding is that each Indian bank files a quarterly Form No. 16A with the Indian Income Tax Department. The form reports the gross interest income and the amount of withholding.
The bank statements and/or the passbooks also clearly each time the interest amount was posted and the Indian Income tax withheld.
So if you have either the Form 16A or the history for the calendar year, you will have the amount of interest earned and the amount of Indian Income tax withheld for the calendar year. You just have to add them up and convert/translate the amounts into U.S. dollar.
