That is certainly the story on PW's weekly charts this week. Just about one-third of the four lists are new titles, including nine mass market debuts and six hardcover fiction newcomers. Both these lists illustrate how tough it is for a book to get a long run on some of the charts and the difficulty in racking up the weeks on these lists. In hardcover fiction, only four of the top 15 have been on the charts for more than a month; in mass market, six have tenures of more than a month. Contrast those numbers with the trade paperback list, on which 13 titles have resided for more than a month.