The Frankfurt Book Fair opened for business Wednesday with publishers talking about their hopes and fears for the new e-books, which are sold as computer files instead of paper and ink. During the fair, 7,500 exhibitors are displaying books to trade buyers from around the globe. Books themselves are not for sale at the Fair, which was created for book publishing companies to do deals with one another and reach out to the bookselling trade, according to dpa. Some 172,000 square metres of booth space has been sold at the huge German fairgrounds. Publishers from 111 nations are attending, many of them to buy translation rights from the big English-language publishers who dominate the world book trade. Last year's event attracted 290,000 people, many of them Germans hoping to catch a glimpse of authors and upcoming books. Nielsen Book, a British company which tracks book sales, predicted the previous day that 10 per cent of US book sales might be in the e- book format by the end of this year. Many publishers are offering readers a choice of digital or print for each title. One third of all new books published in Germany currently are available in electronic format in addition to print, Germany's bookselling and publishing association, the Boersenverein, estimated. It released the data, based on a survey of 80 publishers representing 30 per cent of the market, on the first day of the Fair. But actual sales remain tiny so far. In value terms, e-books make up less than 1 per cent of the German industry's annual sales worth 10 billion euros (14 billion dollars). One quarter of the surveyed publishers said they expected the Apple iPad, which went on sale in Germany in the second quarter of this year, to boost e-book sales. Alexander Skipis, chief executive of the Boersenverein, said German customers should not expect an e-book to be cheaper than the printed version of the same title. He said the development costs to make e-books were enormous. Publishers at the fair said they worried that e-books would cut down overall industry turnover because customers expect e-books to sell for a lower unit price than for the equivalent p-book or print book.