I should probably have said “removed” rather than “arrested”, since not every person removed gets arrested. I am using the DHS’s own statistics <https://ohss.dhs.gov/topics/immigration/yearbook/2022/table3...> which cover every year from 1892 to 2022. For Biden’s term and Trump’s current term I used estimates found in news reports though I don’t have the links in front of me. The estimate for Trump’s current term was just for the first four months of the year.