The number seems to be increasing

I may be confused but doesn't it seem that the suicide bombers are killing more people with each attack? Here's one where 108 died and 240 were wounded. The following chart is courtesy of AFP:

7 July: 105 killed in Amirli market bombing

19 June: 87 die in Baghdad mosque blast

18 April: 190 killed in car bombings in Baghdad

29 March: 82 killed in double suicide bombing in Baghdad market

6 March: 90 killed in double suicide bombing in Hilla

3 Feb: 130 die in suicide truck bombing in Baghdad

22 Jan: 88 killed in Baghdad car bombings