WASHINGTON (AP) — Close the cover on the CIA World Factbook: The spy agency announced Wednesday that after more than 60 years, it is shuttering the popular reference manual.

The announcement posted to the CIA’s website offered no reason for the decision to end the Factbook, but it follows a vow from Director John Ratcliffe to end programs that don’t advance the agency’s core missions.

First launched in 1962 as a printed, classified reference manual for intelligence officers, the Factbook offered a detailed, by-the-numbers picture of foreign nations, their economies, militaries, resources and societies. The Factbook proved so useful that other federal agencies began using it, and within a decade, an unclassified version was released to the public.

After going online in 1997, the Factbook quickly became a popular reference site for journalists, trivia aficionados and the writers of college essays, racking up millions of visits per year.

The White House has moved to cut staffing at the CIA and the National Security Agency early in Trump’s second term, forcing the agency to do more with less.

The CIA did not return a message seeking comment Wednesday about the decision to cease publication of the Factbook.