(NewsNation) — Student visa denials soared between 2015 and 2022, with students from the global south impacted the most, a new report found.

Produced by education company Shoreline and the Presidents’ Alliance, the report found a record of 220,676 student F-1 visas were denied, a rate double that of other types of visas.

While some countries did not experience increased denial rates (including Australia, China, Brazil, South Africa and some European countries) students around the globe were rejected for visas at unprecedented rates. Students in Sub-Saharan Africa experienced the highest denial rates.

To apply for a visa, students must first be accepted into an approved U.S. university. Part of the reason for the denial rates may be due to the fact students are required to prove they have sufficient ties to their home country and intend to return after graduation.

That may be difficult for young people, who are less established in terms of social and economic ties to their local communities.

The rate of denials comes as the U.S. continues to have more capacity to take international students than other nations and may be facing an upcoming enrollment cliff as the number of domestic students decreases. According the report, visa denials could have cost the U.S. roughly $6.6 billion in tuition and living expenses revenue per year.

The report recommends the U.S. education consular officials on what denials are appropriate. Specifically, the authors suggest educating officials that it is not appropriate to deny visas because students are attending lesser-known schools, cannot demonstrate multiple years of funding or have post-graduation interests that could be viewed as grounds to remain in the U.S.