The report released by the Cologne Institute for Economic Research (IW) on Tuesday shows that student housing is getting ever more expensive and hard to find.

The research institute worked with apartment hunting website ImmobilienScout24 and the Deutsche Real Estate Funds (DREF), studying the second half of 2016 for rental prices in 15 university cities.

Munich had the most expensive average rent for a student flat at €17.14 per square metre. This was a 43 percent leap up from 2010 when the average price was about €12 per square metre. And a typical student apartment measuring 30 square metres located close to a university cost €634 when utilities were included.

When looking at rent including extra utilities costs, Frankfurt was the second most expensive city for students at €528 per month on average. Stuttgart came in third for total rent at €499.

Source: Cologne Institute for Economic Research

And while the “poor but sexy” capital of Berlin still seems relatively inexpensive compared to other major cities, its rental prices have skyrocketed in recent years, more so than others. With an average rent of €416 per month, this was a nearly 25 percent increase on 2010 when the average was €333.

The least expensive city was Leipzig at €322 – about half of the average student rent in Munich. Bochum was second most affordable at €344, followed by Kiel at €368.

So what or who is the culprit behind the ever soaring costs?

“Foreign professionals and young workers move to the cities and drive up the prices,” said IW housing expert Michael Voigtländer in a statement.

The researchers also do not anticipate the rapid increases slowing down anytime soon as cities continue to grow.

“The market for student apartments therefore remains attractive for investors,” said DREF CEO Felix Bauer in a statement.

But part of the problem is that cities also are not building enough housing to accommodate everyone given the growing demand, the report notes. The report calculated how many housing units each city needed to build in order to meet demand, and found that only around half of the number of needed living spaces were constructed between 2011 and 2015. The cities of Berlin, Stuttgart and Munich had only achieved 40 percent of their targets.

In particular, cities tend to lack the kind of apartments that students are likely to live in: WG flats, or shared apartments with two or three rooms. Only about one-third of these kinds of apartment spaces were built compared to what IW deemed necessary.