Almost 60,000 hectares of Dutch countryside and farmland have been converted to housing or industrial estates and roads in the past 20 years, the national statistics office CBS said on Monday.

The increase means some 15% of the Netherlands has now been built on, the CBS said. It made the calculation by comparing arial photographs.

Some 75% of the newly built-up land was previously farmland, and residential property accounted for just under half of the developments.

Buildings account for more than half the space in 34 of the Netherlands’ local authority areas, led by Westland (76%), where greenhouse culture dominates. In Rotterdam, 65% of the land has been built on, in Amsterdam 57%.