You got that right! Maybe I'll add a few more screens myself this weekend!
The simple answer to the increase in revenue-per-equipment-dollar is pretty clear and it can be explained in three words: "Airport Express Buses".
If those buses make 16x-17x the CPM (which they do), you'll get a major upward shift in revenue-per-equipment-dollar from the new segment.
Thats one factor. Another is the cost of LCD screens, that cost seems to go down every year from what i've seen. That would also increase the revenue $ per equipment $ ratio.
I took "gross of depreciation" to mean "before depreciation", but I think the rest answers the question well enough... I forgot the airport busses had so much higher CPM and had not considered the impact of decreasing LCD costs