usability study - Why most of the steering wheels in cars is placed in the left side?

I know some countries such as UK has the steering wheels of their cars on the right side. But as we can see, most of the Europian countries uses it at the opposite side. Since I used to drive a car with left-steering wheel I found it impossible to drive a car with right-steer!

Not curiosity, but I am trying to map if this issue is related to User Experience or not.