Total Mail Volume for May, FY 2005 was 800 million pieces or 5.1% over SPLY... First-Class Mail volume improved by 186 million pieces or 2.5%, and Priority Mail grew by 10 million pieces or 16.1% compared to the previous year. Standard Mail volumes ... were 503 million pieces or 6.9% over SPLY.
USPS web site
(Adobe .pdf file- click here for the Excel version, or here for the Financials web page.)