The number of nonimmigrant visas issued to travelers from the six majority-Muslim countries in President Trump’s immigration executive order has dropped dramatically since Trump’s inauguration.

Of the foreign travelers who came to the U.S. from the six countries, 2,013 travelers came in April, down from the 2,551 that arrived in March- a 21 percent decrease, according to Roll Call‘s analysis of a State Department report.

That number is almost half the amount of travelers from those countries that came to the U.S. when former President Barack Obama was in office last year, with 4,454 coming into the country.

According to the White House, the six nations mentioned in the executive order are Iran, Libya, Sudan, Somalia, Yemen, and Syria.

There used to be seven countries on the list when Trump first tried to get his executive order through in January, but Defense Secretary James Mattis requested that Trump remove Iraq from the list.

Trump’s travel ban is going before the Supreme Court for review after the 9th Circuit of the U.S. Court of Appeals ruled against it Monday.

Trump retracted his first executive order in January after multiple judges blocked it. The 9th Circuit upheld the orders blocking the travel ban.

It is not clear whether the drop in travelers from those six countries is due to the Trump administration letting fewer people into the country or if it is due to travelers feeling uneasy about entering the U.S. since Trump introduced the ban.