This line chart shows the share of U.S. federal revenue per year that tariffs, aka customs duties, have made up since 1959, when it was 1.2%. Until 1994, figures stayed mostly in the 1.2% to 1.8% range, then declined to 1% in 1999, where figures mostly stayed until poking up to 2.1% in 2019, staying up near there until dipping to 1.7% in 2023.