This document is about providing historical tables and graphs on private pension plans in the United States from 1975 to 2021. It includes data on the number of pension plans, participants, assets, contributions, and benefits disbursed across different plan types such as single-employer, multiemployer, and multiple-employer plans. The data is sourced from Form 5500 filings with the U.S. Department of Labor and provides insights into the trends and composition of the private pension plan landscape over the decades.