I was just poking around at book sales statistics and came across some interesting numbers from the Romance Writers of America website. 

• Romance fiction sales remained relatively steady in 2010, though dipping slightly to $1.358 billion from $1.36 billion in 2009. And romance fiction continued its dominance of the consumer market at 13.4 percent (in terms of revenue of market categories), beating out mystery, science fiction/fantasy, and religion/inspirational titles.
• Across the board, women were important to the publishing industry in 2010. Experian Simmons data shows women are “far more likely to be buyers to begin with (62 percent of all women nationwide compared to 44 percent of men) and are more than twice as likely to buy 10 or more units in a given year: 9.7 percent of women compared to 4.4 percent of men.”5

  Women buyers were the “most dominant in mass market paperback,” accounting for 67 percent of unit purchases. Eighty percent of romance unit purchases were in paperback format in 2010, down from 84 percent in 2009. Not to be ignored, however, is the e-book format, which accounted for 7 percent of unit sales and 5 percent of spending in the romance category.6 In 2010, “women had caught up and surpassed men as [e-book] readers…the influx of women meant the group was made up of readers who were more frequent and more committed to book buying.

• over 100 million adults did not buy a single solitary book in 2010