The iPad is still by far the most widely used tablet for surfing the Web in North America, but it can no longer claim to lord over 90% of all North American tablet traffic. Via AppleInsider, the latest numbers from mobile advertising firm Chitika show that the iPad accounted for roughly 79% of all mobile traffic in the last week of December, a dominant share that was nonetheless a seven percentage point drop from the previous week.

In contrast, Amazon’s (AMZN) Kindle Fire HD saw its traffic grow by three percentage points over the same period to account for 7.5% of all North American tablet traffic while Samsung’s (005930) Galaxy Tab models saw their share increase by nearly 1.5 percentage points to 4.39% of all North American tablet traffic.

Microsoft’s (MSFT) Surface was practically a non-factor in Chitika’s measurements, accounting for 0.4% of North American tablet traffic — even less than RIM’s (RIMM) BlackBerry PlayBook.