In which year do you predict, there will be the next comet or asteroid that hits Earth?

Question: In which year do you predict, there will be the next comet or asteroid that hits Earth?
- Keywords:
  end of the world,
  natural disaster,
  topical
Asked by juggle5 to Alan on 10 Mar 2014.
- Alan Fitzsimmons answered on 10 Mar 2014:
  
  So far we haven’t found any big comets or asteroids that are definitely on a collision course. There are a few that will come close to us in the next 100 years. We observe those ones whenever possible, to make sure there’s no danger. But we haven’t found them all yet, so we keep looking.
  
  Every year a few small asteroids hit us, but they are only a couple of metres across. So they burn up in the atmosphere and explode 20-40 miles above the ground.

Question: In which year do you predict, there will be the next comet or asteroid that hits Earth?