Does anyone have any statistics on how many packages (or letters) the United States Postal Service looses (i.e. does not deliver)? Three weeks ago I returned a book to an Amazon Marketplace seller via Media Mail. They claim to have not received it. According to usps.com the book should have arrived within 4-6 days. So either the seller is lying about not receiving the return (or lost it somehow) or USPS never delivered it. I am positive the address was correct and the proper postage was affixed to the package. My assumption is the percentage of lost packages is very low (< 1%), but I have nothing to backup this theory.