Then answer the questions
Before you can decide what a "shot on goal" is, you must define what a "shot" is. How about an attempt at a crossing pass that the keeper knocks in accidentally - is that a shot (and thus a shot on goal) or an own-goal?
I have observed that there is a lot of scorekeeper subjectivity defining shots, shots on goal, own-goals, etc. A hard shot that a defender gets just enough of a touch on to deflect it past his keeper who is otherwise well-positioned to make a save - is that a shot? a shot on goal? an own-goal?