J. K. Rowling may have given a much needed jolt to the publishing industry last July when the final installment in her celebrated series about the boy wizard, “Harry Potter and the Deathly Hallows,” sold 8.3 million copies in the United States in 24 hours, but publishers still struggled to sell more books overall than they did in 2006, according to the Book Industry Study Group, a publishing trade association. Publishers sold 3.13 billion books last year, compared with 3.1 billion in 2006, an increase of just 0.9 percent, according to Book Industry Trends 2008, an annual report that analyzes sales in the United States. Higher retail prices helped net revenue increase 4.4 percent, to $37.3 billion, from $35.7 billion. The news is unlikely to surprise publishers as they gather in Los Angeles Friday for the second day of Book Expo America, the industry's yearly convention. Booksellers, librarians, authors, agents and reporters are bouncing through a whirl of parties, celebrity appearances (the artist now known again as Prince, Alec Baldwin and Ted Turner are among those showing up) and author book-signings while being bombarded with advance copies and marketing for books slated for the fall season. “It's a time of uncertainty and of overall economic concern,” said David Rosenthal, publisher of Simon & Schuster, who nevertheless said he was, as ever, optimistic about the books he and others have planned for the coming months. He cited “Champlain's Dream,” by David Hackett Fischer, a Pulitzer Prize winning historian, and “Promise of the Wolves,” by Dorothy Hearst, a debut novel in what Mr. Rosenthal hopes will be a long-running series. “It's a Jean Auel type of thing,” he said, referring to the popular “The Clan of the Cave Bear” series about a woman growing up in the time of cave dwellers. In recent months, several large publishers have reported weak results. Random House, the book publishing unit of the German media conglomerate Bertelsmann, showed a 4.9 percent decline in operating profit last year. This month, Random House said that its chief executive, Peter W. Olson, would step down and be replaced by Markus Dohle, who had been the head of Bertelsmann's printing unit. Simon & Schuster, part of CBS, reported a 32 percent decline in operating income in the first quarter, saying that despite bestsellers like “Duma Key” by Stephen King and “Change of Heart” by Jodi Picoult, it could not match the runaway success of Rhonda Byrne's “The Secret” in previous years. The data from Book Industry Trends was as striking for its projections as for what it showed about sales last year. According to the report, the number of copies of books sold this year is likely to fall by 0.7 percent, and growth projected to 2012 will be flat or less than 1 percent each year. “There is an economic malaise that's hitting this business,” said Al Greco, a senior researcher at the nonprofit Institute for Publishing Research and a professor at Fordham's graduate school of business who analyzed the study. “Basically what we're seeing when we look at the entire retail sector is that consumers are obviously very cautious.” Harry Potter, as expected, helped juvenile hardcovers post a 10.5 percent increase in sales, to 301.6 million copies last year. Juvenile books overall, including paperbacks, were up 3.1 percent, to 900.9 million copies. Net revenue in the juvenile segment, the largest of all categories in terms of copies sold, increased to $3.66 billion, from $3.4 billion. Perhaps surprisingly, sales of children's books, which includes the rapidly growing young adult segment, are not expected to rise strongly over the next few years. “If it weren't for Y.A., this sector would be in worse shape than it is,” Mr. Greco said. Religious books had another strong growth year, selling 274.5 million copies, up 4.2 percent from 263.4 million a year earlier. This niche of books, which last year included “Become a Better You: 7 Keys to Improving Your Life Every Day,” a new book from Joel Osteen, the TV evangelist based in Houston, increased net revenue by 6.3 percent, to $2.58 billion. Sales of adult trade books (fiction and nonfiction for the general market, in hardback and paperback), the second-largest segment in terms of copies sold, increased 1.8 percent, to 839 million copies. Net revenue increased 4.3 percent, to $9.58 billion from $9.18 billion. But going forward, the picture looked rather static: the report projects a slight dip in sales this year, down 0.4 percent, with growth of 0.5 percent or less out to 2012. Nevertheless, publishers continue to hope for hits, or even just to sell several books steadily. Stephen Rubin, publisher of Doubleday Publishing Group, a Random House division, was feeling good about several books his group will be pushing at Book Expo, including “The Gargoyle,” a debut novel by Andrew Davidson about a romance spanning the centuries, between a burn victim and a sculptress; “The Road of Lost Innocence,” a nonfiction book about child prostitution in Southeast Asia, by Somaly Mam; and “A Bold Fresh Piece of Humanity,” a memoir by Bill O'Reilly, the host of a show on Fox News Channel. “I think if you've got the goods you can still sell them,” Mr. Rubin said. Sales of mass market books, the smaller-size paperback format in which thrillers and romances are typically published, fell 5.8 percent, to 541.8 million copies, down from 575.1 million a year earlier. These once-popular books seem to have fallen out of favor, even in the romance segment, whose readers are typically very loyal. One segment where the numbers do not tell the complete story, Mr. Greco said, was the professional category, which includes books about business, law, medicine and technology. Although sales were up just 1.7 percent last year and projections are for essentially flat growth over the next few years, Mr. Greco said that publishers and consumers in this market were converting to digital editions much faster than in other books. - NYT __