It'll be definitely higher than in 2014 for sure. I think 2014 was a true anomaly since the large states had no Senate races (CA, NY, TX), the governors' races where mainly incumbents winning re-election, and the Ebola "crisis" genuinely diverted attention from the races that mattered.
Since I believe that the highly educated Dems will *mostly* remain with the Dems at least through 2024, I'll guess 43-47%, probably closest to 46-47%.
Texas had a Senate race that year, but Democrats didn't seriously contest it and Cornyn romped.