Bombing points (Damage Points) are essentially a calculation of tonnage of ordnance dropped on targets. Lusche or some other old statistician may know exactly how it is calculated (how much damage = X points), as I do not. Basically, every target in game is assigned a number as its hardness (Damage needed to destroy it). Once that number has been met by damage, it is destroyed. A player gets damage points by simply damaging, not just destroying. So, if you bomb a hangar and do not destroy it, you will still receive damage points. I think, but am not certain, that damage is a straight statistic. This means that doing 10 pounds of damage on a hangar or a bunker will result in the same number of damage points. In other words, targets do not matter as damage is one single variable.
The same is true for Bombing Percentage. It is determined as Number of Objects Damaged / Bombs Dropped. So, if you drop one bomb and damage 5 objects with that bomb, your Bombing % will be 5.00% in game (effectively 500% and read as such on the website stats sheet).