Total print revenue fell by 18% to £31.7m in the year to the end of September.
In 2011, America's 148,424 self-published print books accounted for 43% of the total print output, Bowker said.
The company said publishing revenue is down 10%; within this total print revenues fell 12% while digital climbed by 11%.
By 2010, total print ad income had been sliced in half, to $22.8 billion, with a meager $3 billion online.
When executives at Wiley learned that the first printing had sold out within three hours, they ordered a second printing immediately, bringing the total print run to 25,000.
Total print revenues, including advertising and circulation income, fell 12% in the first quarter and an improved 9% in the second quarter.
Dominic Carter, commercial director at News International, said in May that the Times and Sunday Times' had 297,000 total print and digital subscribers.
As of early this month, Oxford had sold 841 sets in the United States, out of the total print run of 10,000 sets.
The magazine, which has a total print circulation of 1.5 million readers, had a slight increase in advertising dollars, but not ad pages, last year.
Total print advertising spend in the regional press is three and a half times the ad spend on radio, and equivalent to the combined total for radio, outdoor and cinema.
Johnston Press reported that total print and digital ad revenues fell 8% in the period, an improvement over the 10% decline reported in the half-year to 2 July.
