A UN Office for the Coordination of Humanitarian Affairs (OCHA) report* documents who had been killing whom in and around occupied Palestinian territory for the week of October 31- November 6, 2012  — i.e., until just prior to the current war. The report has separate segments for the West Bank and the Gaza Strip.
Palestinian casualties by Israeli forces in the Gaza Strip:
Killed this week: 1
Killed in 2012: 71
Killed in 2011: 108
Injured this week: 1
Injured in 2012: 291
Injured in 2011: 468
2012 weekly average of injured: 8
2011 weekly average of injured: 9
Sure, but what about Israeli casualties?
Israeli casualties by Palestinian fire from Gaza
Killed in 2012: 1**
Injured this week: 3
Injured in 2012: 19
Thus, according to OCHA reports, there was 1 Israeli death in 2012 due to hostile fire from Gaza — compared to 71 Palestinian casualties by Israeli forces in the Gaza Strip.
Now even one Israeli death by violence is one such death too many. (Of course, by 71 of the same tokens, 71 Palestinian deaths are 71 too many as well.) But like other analyses have suggested , these facts show there’s a bit of a problem with claiming the current hostilities are all Hamas’s fault. However much we’re trained to assume that.
* Via  the “Moon of Alabama” blog.
** This line is documented in the Oct 10-16  report, but (currently) not in the subsequent three reports (Oct 17-23 , Oct 24-30 , Oct 31-Nov 6 ).