Excellent piece by the NZH's enterprising retail reporter, Maria Slade, who seems to specialise in book trade matters:

Vampires take $10m book bite
By Maria Slade reporting in The New Zealand Herald
Monday Jan 18, 2010

Movie adaptations of Stephenie Meyer's Twilight books have been big hits, and big earners.
New Zealand readers spent $10 million on the teenage vampire series Twilight last year.The Stephenie Meyer titles, two of which have been made into hit movies, accounted for just over 4 per cent of all New Zealand book sales in 2009.
The figures come from Nielsen BookScan, the data monitoring and analysis service for the English-speaking book industry worldwide.

From December 2008 all major retailers, accounting for 95 per cent of book sales, signed up to the service.This means booksellers can gain an accurate picture of how sales have tracked over the 12-month period.
The news was fair to middling.
In the last four weeks of December 2008, New Zealanders bought 1.56 million books, worth $39.9 million.
This compares with unit sales of 1.55 million in the same period in December 2009, a decline of 0.6 per cent. However value was up 1.5 per cent, at $41.5 million.
Overall $239 million on books was spent in 2009 ($229 million without the Meyer books). Non-fiction accounted for 49 per cent of that, with fiction at 26 per cent and children's books 25 per cent. The results may have been flat but other retail sectors probably looked on with envy.

Books had done better than the books and stationery category as a whole, Paper Plus chief executive Rob Smith said.BNZ credit card and Eftpos data showed the category was down almost 3 per cent for the year.Paper Plus had put a new focus on books, such as placing books at the front in its new store layouts and concentrating on the top 100 bestsellers. As a result the chain had seen growth in book sales during the year.
Books tended to be more recession-proof than bigger ticket items and were a product consumers could turn to for a little bit of escapism, he said.
The year may have been flatter if it weren't for big sellers like Dan Brown and the Twilight series. "Stephenie Meyer was definitely one out of the box, it was very good."

Wendy Tighe-Umbers, who owns the independent Time Out bookstore in Mt Eden, said the hot one for her store over Christmas had been the Stieg Larsson Girl with the Dragon Tattoo trilogy. "We just couldn't keep that in stock." The store's December 2009 sales were up on the previous year, boosted by the fact that virtually every big name author - such as Barbara Kingsolver, John Irving, Sebastian Faulks and AS Byatt - had new books out for Christmas, she said.

Hamish Wright, chairman of Booksellers New Zealand and owner of Wrights Bookshop in Cambridge, said booksellers' results for 2009 had varied from 5 per cent up to 5 per cent down. His own business, affected by leaner times in the dairying and agriculture industry, was down about 4 per cent. He agreed there had been plenty of titles to sell in 2009.
People were talking about 2010 being the year of the e-book, but he was "not completely convinced".
REDgroup has announced its Whitcoulls and Borders chains will start selling digital books in May.
Tighe-Umbers said she would probably have to "keep up with the play" and offer e-books, but she said digital downloads could never replace the customer service element of her business.