While I don't think your numbers are correct, I want to explain: Hamas brought this about. They had their choice, and they have been warned before. This is not a case of a merciless aggressor randomly slaying civilians.
Westerners see retaliation as a way of stopping any further offenses.
And in regards to the IRA here's Mark Steyn...
That, by the way, is the one point of similarity between the jihad and conventional terrorist movements like the IRA or ETA. Terror groups persist because of a lack of confidence on the part of their targets: The IRA, for example, calculated correctly that the British had the capability to smash them totally but not the will. So they knew that while they could never win militarily, they also could never be defeated. The Islamists have figured similarly. The only difference is that most terrorist wars are highly localized. We now have the first truly global terrorist insurgency because the Islamists view the whole world the way the IRA view the bogs of Fermanagh: They want it, and they've calculated that our entire civilization lacks the will to see them off.
Extra - WSJ.com
When America is strong the world is calm, When America is weak tyrants and terrorist slaughter the meek. ~ SgtRock