From news reports:
Stamped mail is the category that has declined most steeply in the last decade — 47 percent since 2001. “Standard” mail, the official euphemism for junk mail that until 1996 was called third class, dropped only 8 percent over the same period.
The decline in mail volume has been accompanied by widening losses: $8.5 billion for 2010, and a projection of nearly $10 billion for 2011.