You can’t count the seats where no candidate was fielded. The GOP didn’t contest 24 seats.
The numbers I posted were for the contested seats.
There are reasons R’s don’t contest seats, and D’s don’t contest seats. Because they have absolutely no chance of winning.
When a major party doesn’t field a candidate, sometimes a third-party or independent files. In any case, in Virginia, you can write-in a candidate.
The votes for third-party and indy candidates in races without a major party candidate is always much larger than when both major parties are represented. Ditto write-ins. There are few write-ins when both major parties are represented, and a big percentage when only one major party is represented.
There potentially are other votes missing. For example, the drop-off from the Presidential vote. But, this is difficult to estimate in a year when you don’t have a Pres., U.S. Senate or Gov. race. I could maybe jimmy up an estimate as best as possible in the absence of a statewide race, but I don’t have the time.
You are assuming the Republican vote in a Democratic district will equal the average Republican vote in contested races. This is way wrong.