More than 18 million Call of Duty: Black Ops map packs have been sold, reports publisher Activision.

Activision Publishing CEO Eric Hirshberg said that with the map packs taken into account, the average Black Ops gamer had spent US$76 on the game. That’s an 18 per cent mark up on the game’s retail price.

Map pack sales for Black Ops dwarf those of other Call of Duty titles: World at War sold nine million map packs and Modern Warfare 2 sold 11 million map packs.

According to Hirshberg, consumer engagement in Call of Duty is at an all-time high: “There are over 30 million unique players of Black Ops who collectively have amassed, incredibly, more than 2.3 billion hours of play. To put that number in perspective, that's more than a quarter of a million years of play and that means our millions of fans spend more time per day on Black Ops multiplayer than they do on Facebook.”

The next Call of Duty title, Modern Warfare 3, is due in November.