Asahi Breweries Ltd. maintained its position as Japan’s biggest beermaker last year, widening its market-share advantage over Kirin Holdings Co. as demand in the nation fell for a seventh straight year.

Asahi had a 37.9 percent share of shipments for standard, low-malt and no-malt beer last year, ahead of Kirin’s 36.2 percent, the Tokyo-based brewers said today in separate statements. Industrywide sales dropped 3.7 percent to 442 million cases, the lowest level since records began in 1992.

Kirin’s 2011 share dropped from 36.7 percent in 2010, as Japan’s strongest earthquake on record, ensuing tsunami and nuclear accident disrupted beer production. Sales of its “Ichiban-Shibori” brand fell 2.1 percent last year. Asahi said demand for its “Super Dry” and “Clear Asahi” brands helped the company maintain its market share.

Asahi and Kirin forecast beer demand in their home market will drop by 1 percent to 2 percent this year, while Suntory Holdings Ltd. (SUNTZ) predicts a 3 percent decline as the population ages and shrinks.

Suntory’s share in 2011 was 13.3 percent, the highest on record for the company. Sapporo’s was 11.6 percent.

Asahi rose 0.6 percent to 1,726 yen as of 10:39 a.m. in Tokyo trading. Kirin gained 0.6 percent and Sapporo rose 0.7 percent.

A case of beer in Japan is equivalent to 12.66 liters (3.3 gallons).