Okay, so my dyslexia got the best of me this morning...it's actually 46% of the worlds mail (not 64% as I indicated below). That was last year's estimate...could've changed since then...still impressive none-the-less?!
Here's the link:
http://www.usps.com/communications/n..._2007_0420.htm
Here's the text:
An independent federal agency, the Postal Service is the only delivery service that visits every address in the nation — 146 million homes and businesses — six days a week and also has 37,000 retail locations. It relies on the sale of postage, products and services to pay for operating expenses, not tax dollars. USPS has annual revenues of $73 billion and delivers more than 46 percent of the world's mail volume.