Paywalls still seem to be paying off for newspapers.

The industry's average weekday circulation over the six months ending in September slipped just 0.2% from the equivalent period a year earlier, according to the latest biannual report from the Audit Bureau of Circulations. Sunday circulation increased 0.6%.

The numbers aren't quite as good as in the last report, when weekday circulation increased 0.7% and Sunday circulation jumped 5%, but they're again far better than the big declines seen just two or three years ago and reinforce the notion that paywalls around digital content are helping newspapers' circulation business.

Digital circulation comprised 15.3% of all U.S. newspaper circulation in the six months ending in September, the Audit Bureau said today, up from 9.8% from the period a year earlier.

The Wall Street Journal, the country's biggest newspaper by combined print and digital circulation, reported average weekday circulation of nearly 2.3 million, up 9.4%.

USA Today's average circulation slipped 3.9% to 1.7 million. It will be looking for a better performance in the next report after introducing a redesign last month, but does not charge for digital.

The New York Times increased 40.3% to 1.6 million as weekday print fell 6.9% to 717,513 and digital grew 135.8% 896,352. The Times introduced the pay meter on its site and apps in March 2011.

The rules for reporting circulation mean that not every unit of growth reflects a new reader; a newspaper can count paying readers twice if, for example, they pay for both print and digital.