From the Document: "[T]he purpose of this letter is to provide an update on the overall status of the Department of Homeland Security's (DHS) implementation of GAO [Government Accountability Office]'s recommendations and to call your personal attention to areas where open recommendations should be given high priority. In November 2020, we reported that on a government-wide basis, 77 percent of our recommendations made 4 years ago were implemented. DHS's recommendation implementation rate was 84 percent. As of March 2021, DHS had 464 open recommendations. Fully implementing these open recommendations could significantly improve agency operations."
Government Accountability Office: https://www.gao.gov/