What kind of gas milage does a 5.9 2000 dodge ram ext cab get?

I have the same truck and still have the window sticker,

it says average 12 city and 17 hwy.

my truck has about 105,000 miles and I'm averaging about 7mpg in the city and around 11 on the hwy. I did swap my 4.10:1 diff gears for 4.88:1 when I did this it only dropped 1 point.