Sounds about right, especially if you're an AT ... for some reason they seem to do worse (as compared to the MT) than you'd expect. Also depends on mods/gear ... but you probably knew that. If you're running larger than stock tires, you'll get a bit back from accounting for the difference, but not the 20-30% I expect you're looking for (assuming you want to be in the 20s).
The hit you take from big tires, lots of gear, armor, etc can be offset by the combination of intake manifold spacer (IMS), intake, exhaust and a good tune ... but the best folks seem to do on a regular basis is the high teens, in a relatively stock configuration and lightly loaded. It's just not going to be a fuel sipper, unfortunately.
What are/were you hoping for? I tend to get right around 16/17 in mixed driving on my MT ... with big aggressive tires (was Toyo MTs, now the ST-Maxx), skidplates, sliders and a rack ... maybe a tick higher if I'm headed down from the mountains. Best I ever did was bone stock, coming back from a weekend in the Sierras to the Bay Area, I think I hit 21/22 and that was primarily due to being able to coast a ton ...