It's been 15 years - mostly the ones that were in a state to be completed have been, and any that were abandoned fifteen years ago and left untouched in that time are likely (a) in the middle of nowhere and not particularly sustainable or (b) in such poor state that it'd be a knock and rebuild job.

A lot of it is a consequence of the collapse of the building trade in 2008, population growth and poor regional planning forcing everyone into the cities