A large-scale survey conducted by Tokyo's Edogawa Ward has found that nearly 8,000 people age 15 and older are considered to be hikikomori, or people who have isolated themselves from society at home for more than six months.

The results, which were released Wednesday, showed that the largest proportion of social recluses in the municipality were people in their 40s, at 17.1%, followed by those in their 50s, at 16.6%.

Edogawa’s survey, based on responses from 103,000 households, is unusual because the questionnaire was sent to every resident in the ward age 15 or older who was suspected of being a shut-in. The ward made the judgment based on them not having paid income taxes or not having used nursing or disability services provided by the government.