Ever wonder how much data you burn through every month on average? If you're an Android user within the US, odds are that it's quite a lot. The NPD Group estimates that Americans of the Google persuasion typically consume about 870MB of data on cellular networks every month. While it's not an extreme amount next to the 2.5GB of WiFi usage, it's enough to give anyone second thoughts about coasting on a basic data plan -- and a reflection of how both 4G and media apps have changed our behavior. Not surprisingly, it's a younger crowd more comfortable with smartphones that's the most aggressive: the 18-24 set races through 1.05GB a month where the 55-plus audience uses a more modest (if still healthy) 750MB. We don't yet know how iOS stacks up in current conditions, but the NPD is promising a comparable look soon. Something tells us the iPhone 5's LTE will lead to just as much voraciousness.