Bulk Import for customer account type

There is a standard field called Account type at the customer account level which has 2 Out of the Box values: Internal (I) and External (R). I created a new value called Distributor (D). I wanted to fill this value to a considerable customer accounts so I thought I will do Bulk Upload using FBDI. But in the FBDI sheet, the account type is a dropdown with values I/R. I cant add the customer value that I created. Is there any other way to bulk upload?