James Patterson and Stephen King might still top Forbes' yearly round-up of the world's richest authors, but the magazine is predicting its list will look a little more female-friendly next year.

Forbes, which calculates its annual compilation by using official figures and talking to book industry experts, found that Patterson earned $94m last year – a period which saw him publish 14 new titles and make more than double the amount of the second-placed King. Nine of the top 15 slots on the list were taken by male authors, including King (who earned $39m thanks to the release of his doorstopper novel about the assassination of JFK, 11/22/63), legal thriller writer John Grisham ($26m), Wimpy Kid author Jeff Kinney ($25m) and newcomer George RR Martin, who made $15m following the adaptation for television of his Song of Ice and Fire fantasy series.

The highest-ranking female writer on the list was Janet Evanovich, in third with earnings of $33m, but Forbes believes next year will present a very different picture. Not only will Suzanne Collins benefit from the full portion of the proceeds from the first Hunger Games film, and JK Rowling from the release of her first adult novel The Casual Vacancy this September, but EL James' record-breaking earnings from the erotic Fifty Shades trilogy, which sold 20 million copies in four months, will assure her "a place near the top of next year's top authors list", according to Forbes.

"At the height of Fifty Shades mania, the erotic novels were estimated to be generating as much as $1.3 million per week for their author, EL James. And that's not counting the $5 million she received from Universal Pictures and Focus Films for the theatrical rights," said the magazine, suggesting that perhaps Twilight author Stephenie Meyer, who made $14m last year, might deserve a cut as "James's books originated as works of Twilight fan fiction".

James Patterson: $94 million

Stephen King: $39 million

Janet Evanovich: $33 million

John Grisham: $26 million

Jeff Kinney, $25 million

Bill O'Reilly: $24 million

Nora Roberts: $23 million

Danielle Steel: $23 million

Suzanne Collins: $20 million

Dean Koontz: $19 million

JK Rowling: $17 million

George RR Martin: $15 million

Stephenie Meyer: $14 million

Ken Follett: $14 million

Rick Riordan: $13 million