No set figures but when laning your usually well under 1500 revs and trundling along less than 5mph, so not much used.
When offroad at a pay or play like at my friends farm yesterday and the engine was gunning it most of the time between 3000 rpm and lots of times red lining at 4000 rpm as I ws getting determined

to get up lots of mud.
So consequently you use more when gunning it, less trundling, but mile for mile you will use slightly more fuel as the engine is operating two axles.