The heats of combustion of the more and less stable stereoisomers of the 1,2-, 1,3-and 1,4...

The heats of combustion of the more and less stable stereoisomers of the 1,2-, 1,3-and 1,4-dimethylcyclohexanes are given here. The values are higher for the 1,2-dimethylcyclohexanes than for the 1,3- and 1,4-isomers. Suggest an explanation.