Putting down a marker on eating the ICE infrastructure away
Been looking for data like this for a long time:
Turns out that California Energy Commission has gasoline data, lots of gasoline data. I downloaded and edited the data above.
I've argued since 2013 that as EVs start taking up significant market share, the gas station and repair infrastructure for internal combustion engines will start to shrink and become less convenient. A similar-but-distinguishable process will happen with increasing ICE mileage, but that process stabilizes because even high mileage ICE vehicles still need gas and will pay enough to stabilize the number of stations. As EVs eat into the ICE infrastructure, the ICE market just gets less convenient and the shift to EVs accelerates in a virtuous feedback.
The effect will be especially strong when people consciously notice the ICE infrastructure is getting less convenient, but that's not required. And I fully admit the more important factor, for now, is EVs becoming more convenient. Still, a choice of EV versus ICE turns in part on the relative convenience of the choice, and increasing inconvenience for ICE will have an increasing effect.
Oslo would be the best place to test this, but I can't find their data. San Francisco Bay Area isn't a bad alternative. This doesn't constitute proof yet - 2016 was the highest year in the dataset, and it would be bold to claim the 2017 decline is from EV share of the fleet mileage traveled, but let's watch this space.