From Deliver Magazine (Issue 24, Page 7), has a simple infographic that clearly breaks out what's in your average mail delivery in the U.S. The illustration is by Jude Buffum. Its available here as a PDF.
Source: USPS® Household Diary Study: Mail Use and Attitudes, FY 2007
Randy is currently President of InfoNewt, an infographic design and visual consulting company. InfoNewt works with clients to develop visual communications and strategies to reach their target audiences. These are designed for use in presentations, social media, training and print.