The estimated number of children aged under 15 in Japan fell to 15.12 million as of April 1, hitting its lowest level since comparable data became available in 1950, the internal affairs ministry said Monday.

The figure was down by 200,000 from a year before, marking its 39th straight year of decrease. The ministry released the estimate a day before Children's Day.

There were 7.74 million boys and 7.38 million girls. The share of children in Japan's total population was 12.0 percent, falling for the 46th straight year.

By three-year age bracket, the number of children aged 12 to 14 was the largest, at 3.21 million. Those aged nine to 11 totaled 3.18 million, six to eight 3.04 million, three to five 2.93 million and zero to two 2.75 million.

Tokyo was the only prefecture that posted growth in the number of children as of Oct. 1 last year, with an increase of 3,000 from a year before to 1,553,000.

Kanagawa and Osaka prefectures saw their number of children exceeding one million.

The share of children in the total population was highest in Okinawa, at 16.9 percent, followed by Shiga, at 13.8 percent, and Saga, at 13.5 percent.

The share was lowest in Akita, at 9.8 percent, the first reading below 10 percent in any of the country's 47 prefectures since data began in 1970. It was followed by Aomori, at 10.7 percent, and Hokkaido, at 10.8 percent.