The real internal argument among art editors seems to be, how dark or light should it be, and how much green should you add. I looked at our new title areas, which for our purposes, consisted of the front table paperbacks, new and noteworthy hardcover fiction, Boswell's Best, and new mysteries and thrillers (mixed cloth and paper).
I divided the books up by green enough to be perceived as turquoise, and not green enough to be perceived as turquoise. There really is a lack of purplish blue (mysteries seem to tread slightly into the purple tone, such as Laurie King's The God of the Hive), so that wasn't in the equation. Like green and orange, you rarely see high-profile purple jackets, with few exceptions. More on that in another post.
There was another set of books where the blue was so discolored as to almost be gray. I decided to make that a different category, though in my arbitrary fashion, I mixed dark and light blues of the same family together. Many of these books feature sky (which probably a major cuase for the prevalence of blue), but in a more naturalistic tone. Sue Miller's The Lake Shore Limited split the difference, with a blue on the top half of the jacket and a turquoise on the bottom.
In the end, blue beat turquoise by a healthy margin.