PDF version of the report is here.
The NPA routinely collects information on demographics, policy, and the organizational structure of postdocs and postdocs resources at institutions throughout the US. Summaries of their findings can be found here. Login to your NPA account to access even more information! (Reminder: NPA membership for UMN postdocs is supported by the PDA, so join for free using this link (choose "Affiliate Individual Member, Postdoc").