President Donald Trump this weekend lamented what he characterized as an invasion of illegal immigrants that is “very unfair to all of those people who have gone through the system legally and are waiting on line for years.” But illegal border crossings represent a relatively small share of the number of people who enter the country, legally or otherwise, in any given year, according to the Department of Homeland Security’s data. A September 2017 Office of Immigration Statistics data brief estimated that in fiscal year 2016, the latest year for which complete data is available, there were 170,000 successful illegal border crossings occurring outside of authorized ports of entry.