The findings emerged from a survey of 150 US media markets undertaken by Scarborough on behalf of the Newspaper Association of America. The next largest grouping was the 15% who read their local newspapers both in print and online, while an additional 10% read newspaper content on a mobile device, as well as print and online. Print and mobile accounted for a further 4%.
Digital only readers made up 15% of the total, divided between online-only readers (7%), while a web/mobile combination (5%) and mobile-only (3%).
Poynter, the journalism school, said the digital audience was younger and their share was likely to increase as newspapers developed their smartphone news offerings.
And while the print-only readership was shrinking it was still a "well-defined, upscale audience … attractive to advertisers". But Poynter suggested that advertisers would move to digital more quickly than these readers, scaling down print ad budgets as they did so.
An earlier analysis for the Newspaper Association of America found that daily circulation figures were rising, driven by digital gains at the largest newspapers.
The five newspapers with a circulation of 500,000 or more saw a 22.3% increase in circulation in the six months ending September 2013, compared to the same period a year earlier.
Most, however, reported that print losses had not been offset by the digital audience, with smaller titles suffering most. Newspapers with circulations below 25,000 saw their total circulation slip 3.9%, while papers with a circulation between 25,000 and 50,000 were down 4.6% and those with circulations from 50,000 to 100,000 dropped 3.7%.
Larger titles with circulations between 100,000 and 250,000 fell just 0.9% and those ranging from 250,000 to 500,000 were down 1.1%.
Overall, print circulation was declining as a share of total circulation and now stood at 71.2% for dailies and 74.9% for Sundays.
Data sourced from Poynter; additional content by Warc staff