Activision has sold 18 million Call of Duty: Black Ops map packs, the publisher has announced.

CEO Eric Hirshberg revealed the figure during an investor event in Los Angeles earlier today, adding that users have spent an average of $76 on the game - an 18 per cent increase on the sticker price.

In comparison, World at War sold nine million map packs in its first nine months on sale. At $10 per pack, that equated to an average user spend of $68. Modern Warfare 2 sold 11 million downloads over the same time period, at $15 each.

Hirshberg went on to claim that "consumer engagement" in its FPS franchise 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 entry in the series, Modern Warfare 3, arrives this November. Map packs may well follow.

Call of Duty: Black Ops and Call of Duty: Modern Warfare 2 were the two most active titles on Xbox Live last week.

According to Microsoft's Major Nelson, Black Ops took over the top spot from Infinity Ward's Modern Warfare 2 in its first week on release. Call of Duty: World at War wasn't too far behind either, coming in at seven.

Kinect Adventures was the only Kinect title to make it into the top 20, landing at 16. Here's the full list:

1. Call of Duty: Black Ops
2. Modern Warfare 2
3. Halo: Reach 

4. FIFA Soccer 11 

5. Fable III 

6. Fallout: New Vegas
7. Call of Duty: World at War
8. Madden NFL 11
9. Call of Duty 4 

10. Halo 3
11. NBA 2K11 

12. GTA IV
13. Red Dead Redemption
14. Gears of War 2
15. Battlefield: Bad Co. 2 

16. Kinect Adventures 

17. Medal of Honor
18. NHL 11
19. Forza Motorsport 3
20. FIFA 10

Ubisoft's retro rump-kicker Scott Pilgrim vs. The World was the most downloaded Xbox Live Arcade title, followed by Yu-Gi-Oh! 5D's Decade Duels and Cave's excellent shmup Guwange. The full top 20 looked like this:

1. Scott Pilgrim vs. The World
2. Yu-Gi-Oh! 5D's Decade Duels
3. Guwange
4. Super Meat Boy
5. Faery: Legends of Avalon
6. Dead Rising 2: Case Zero
7. Plants vs. Zombies
8. Risk: Factions
9. The King of Fighters 2002 Unlimited Match
10. Limbo
11. Trials HD
12. Peggle
13. Castle Crashers
14. Sonic the Hedgehog 4 Episode I
15. Bloody Good Time
16. Sonic Adventure
17. Game Room 

18. Snoopy Flying Ace
19. 3D Ultra MiniGolf Adventures 2
20. Family Game Night