Further evidence that Brexit is deterring European Union workers emerged in figures published Tuesday.

The number of EU nationals working in the U.K. in the three months through June plunged by 86,000 from a year earlier to 2.28 million, the biggest decline since records began in 1997, the Office for National Statistics said in a report.

The 3.6 percent drop was driven by citizens of the eight countries including Poland and Hungary that joined the EU in 2004. They’re being deterred by a weakened pound, which makes their earnings in the U.K. worth less when repatriated, and the prospect of migration curbs once Britain leaves the bloc next year.

Concerns about the surge in foreign arrivals over the past decade was a key reason why 52 percent of Britons voted for Brexit in 2016, though lawmakers have yet to decide on what kind of immigration system will replace the EU’s free-movement policy.

Prime Minister Theresa May is pledging to reduce total net migration to the tens of thousands, and industries such as farming, food and hospitality are already reporting labor shortages.

Separate ONS figures published in July show that the number of EU citizens coming to the U.K. looking for work has plunged since the referendum. A government-commissioned report published earlier this year showed that businesses have become reliant on EU workers and are concerned about migration restrictions after Britain leaves the bloc, especially in lower-skilled sectors.