More libraries are offering free membership to people over 18  to promote reading and combat dwindling visitor numbers, new figures show.

Libraries are already free for schoolchildren but some 40% of local councils have now extended the measure to some groups of adults, mainly people in their 20s, broadcaster NOS reported.

“Libraries want to spread the message that anyone who is still studying or has just finished their studies is welcome to use the library for free,” researcher and librarian Mark Deckers said.

By the end of the last century libraries had some 2.3 million, mostly paying, customers. That number has almost halved to 1.2 million.

But according to Deckers the downward trend has been stopped by the free passes for people over 18.

Spijkenisse library boss Victor Thissen said the only way to lure back the over-18s is to make membership free. “We realised teenagers stopped coming to the library just before turning 18. They could not or did not want to pay the €10 or €20. No way would we have got them back otherwise,” he said.

His library is looking at extending the membership to people up to the age of 65 but with a lending limit of five books a year.

The free membership is also aimed at improving plummeting reading skills and the motivation to read, Twente librarian Frederica Westera said. Once this group is in, the library can gain better insight in their reading behaviour, she said.

The Spijkenisse library makes up the lost income through its cafeteria while other libraries get more financial support from their local authority.