 One of the conclusions rests on comparisons between Sweden and surrounding Nordic countries (see NIKK study above).Some have considered the numbers on street prostitution in Denmark to be over reported, based on a report from the Danish prostitutes' organisation Sexarbejdernes Interesse Organisation (SIO).SIO stated that street prostitution in Copenhagen was overestimated by 1000 persons, attributing over reporting to an NGO, Reden, that works with women in prostitution, and the numbers of women that they had seen.