[Kate Schandler]

Michelle,

Try creating a New Donor Acknowledgement Letter file. On the General tab, select "Gift Date" and "Last Calendar Year" and then on the Fields to include tab, start with "One letter per donor."

I will admit, I have never run this particular letter this way, but it is designed to work that way. You could also create an export and use the "Total Amount" field, which would allow you a few more filters then the Mail file would.