Here, this is a decent perspective... and this is 10 years ago.
http://the.honoluluadvertiser.com/article/2008/Dec/07/bz/hawaii812070331.html

 Banks surveyed earned $1.97 billion in overdraft-related fees in 2006, representing 74 percent of their overall $2.66 billion in service charges on deposit accounts.

In total, overdraft-related fees bring in $17.5 billion each year to banks and credit unions, estimates advocacy group Center for Responsible Lending.

Large banks are more likely to process transactions from largest to smallest dollar amount, often triggering more fees.

Young and low-income consumers are disproportionately affected by overdraft fees.

"Banks are generating the bulk of their fees off the most vulnerable account holders,"