Extract from Publishing … and Other Forms of Insanity site:
Determining the most popular fiction genres is not as straightforward a task as it may seem. Is popularity judged by how many people say they prefer a certain genre, by books actually read, by revenue, or by books published? Each of these questions will yield a different answer.
Time period is also a consideration. Are we looking at last year’s books, last decade’s books, or all-time publishing and sales records? The infographic to the left from Ebook Friendly is a compilation of all book sales for which there are figures. Children’s books are clearly the winner. But one has to take into account the boost in sales generated by the Harry Potter series, which alone generated $25 billion in revenue, selling more than 400 million books worldwide. And while the Harry Potter books may be classed as children’s fiction, they may also be classed as cross-over, fantasy, and magical realism.
Given these complexities, let’s break down what is meant by popularity based on what people say they read (which encompasses books people borrow from libraries), which books are sold, which genres generate the greatest revenue, and which books agents and publishers predict will sell, as these will produce the greatest number of contracts.