Approximately what percentage of roadside litter flies out of the back of pick-up trucks

Approximately 51% of roadside litter flies out of the back of pick up trucks.

According to the Texas department of Transportation, more than half of road side litters in Texas fly out of back of pick up trucks. The habit of putting litters at the back of the truck is considered to the same as throwing the litters out of the window and efforts are been made by the government to stop this type of littering.