Nearly one-fifth of the ballots mailed out late last week for the Nov. 6 general election have been marked and returned to the Douglas County elections office. By this morning, 11,468 of the 52,267 ballots — 18.4 percent — sent to registered Douglas County voters had been turned in, said Jeff Doty, the county’s chief deputy clerk. “That’s a bit ahead of where we were at this time four years ago,” Doty said. The big difference is in the number of registered voters this year compared to four years ago. A total of 3,660 fewer Douglas County residents are registered …