The Bank of Japan is counting brothels in Hokkaido to help determine demand for services as the country battles its deepest postwar recession.

The number of sex parlors in the Susukino red-light district in Sapporo have more than quadrupled in the past 20 years, according to a central bank report Wednesday titled, "Susukino, Recent Trends and Changes to a Pleasure District." The number of eateries fell to 3,620 from 4,191 during that period, the BOJ said.

The survey of sex shops and restaurants was designed to better gauge demand for services, an area of the economy that's becoming more important as exports slump.