As disquieting as this is, it has had two unintended consequences, at least for the terrorists. First, most of the casualties from the most recent (in the last two years) suicide bombings, have been Afghan civilians. The reason for this is a lack of competent support staff. Suicide bombings tend to focus attention on the suicide bomber. But he (it's usually a he) is a relatively minor player in these attacks. In fact, some suicide bombers are unintentional heroes, thinking they are just moving the the explosives, and unaware of the wireless detonation mechanism which will set the bomb off before they can get away, or become aware that they are moving a bomb.
What makes suicide bombing relatively efficient is a team of experienced support people. There has been a lack of such staff in Afghanistan. This has caused bombs to go off at the wrong time, or not at all. This has resulted in the suicide guys getting lost, or otherwise showing signs of poor preparation.
To carry out an effective suicide bombing operation you need bomb builders. In Iraq, these experts work for money (up to $20,000 per job, usually using a stolen car). Not too many of these fellows in Afghanistan. And once you build the car bomb, you need a "delivery teams" to pick it up and delivered it to the "deployment team". This crew scouts potential targets, picks the most likely one, then works out how to get the bomb car in position.
Separate from all this is the suicide bomber recruitment and training team. There are a number of specialized skills needed here, and people possessing well developed skills in this area do not appear to be in Afghanistan. Many suicide bombers have been captured alive in Afghanistan, and these fellows appeared to be poorly selected and inadequately trained.
Your average car bomb had several hundred pounds of explosives, either in the form of artillery or mortar shells, or bulk explosives. Detonators on the shells, or stuck into the blocks of explosives, are connected to a electromechanical switch, a wireless device or a timer. In Iraq, the quality of the car bombs kept improving until 2005, then it began to decline, as more and more garage owners and mechanics backed away from the car bomb business. None of them appear to have gone to Afghanistan, although there have been rumors of Iraqi technical experts being brought in. Most likely, the Afghan suicide bomb support teams are getting their technical knowledge from terrorist oriented web sites.
From the onset of fighting in Afghanistan in October of 2001, through the end of 2003, there were no more than one or two suicide bombings a year. This jumped to about 6 in 2004, more than quadrupled to about 26 in 2005, and from January through July of 2006, has doubled again, to about 55.