I thought it would be more than a quarter...;)

The Sofia Weekly: A quarter of the Sofia citizens suffer from some kind of mental disease, a research of the Sofia City Hall showed. The mental diseases of the Sofia citizens lead to decrease and even loss of the ability to work, state the results of the research, which is part of the municipal strategy for mental health. Some 6,000 citizens of the capital city suffer from schizophrenia and another 25,000 individuals have learning disabilities.