PDF of a report from 2010:
This report employs the latest data available to answer a very important
question: what contribution is made to our economy by industries that
depend on the limitations to copyright protection when engaged in
commerce? As this report shows, such industries make a huge contribution.
In an era of highly competitive markets for information goods and
services, changes to the boundaries of copyright protection will alter
the economic landscape. Broader regulation of economic activity by
copyright might encourage additional creativity, but it will deter certain
types of technology innovation, and may undermine competition and
free expression. Our information policy must therefore balance the
incentives that IP regulation creates against the disincentives that
result. For 300 years, copyright law has recognized this fragile balance.
From Wired.com PDF [PDF]