It's the majority, but overwhelming or not surprisingly appears to depend on car model, at least per some calculations someone on reddit ran [1].

I'd add though that rolling resistance tends to be higher, on average, in winter too. When there's often a bit of snow on the roads... Less so on high speed highways admittedly.

[1] https://www.reddit.com/r/askscience/comments/l2cq6b/comment/...