I have a couple of thoughts

Another thing to consider is similarities in your choice of friends. Perhaps everyone geographically lives in the same type of areas with things like superfund sites or pollution. Also most of us make friends that share the same interests we do. Not to sound like a complete ass, but maybe you and your friends share interests that aren't very healthy.
In general though, the older we get, the more we watch people around us die. When I was younger it wasn't common, but in the last 10 years I've had a few friends die too. My dad (58) just told me the other day how he is really starting to feel discouraged because so many people he's known have died. I'm thinking there probably is a positive correlation between age and the number of deaths one experiences. At any rate, I certainly don't think you are alone.

I think if I was on your friends list I'd unfriend you.

Don't freak out.

The thing is, people get a bit mixed up over how 'chance' works. It's human nature.

You're noticed something that's happened to 3 out of a 100 people. Even ignoring things like it's not a random choice, it's 100 of the type of people you befriended, then even so, the chances of someone under 50 dying from aids might be low, for your group of people. The chances of peole under 50 dying from heart disease might also be low. So you're thinking, oh wow is somehting going on. Because you HAVE a group which has 3 deaths from these diseases, and you're working backwards.

Let me put it another way. There are MANY things which might have a 1 in 100 chance of happening. Perhaps some illnesses, things which typically happen to people. This is a national statistical average. HOWEVER if you examine your group, you might find that none of these things has happened to them.

In other words, things like "1 in a 100" does not mean EVERY group of 100 people will have 1. Depending on other factors (the 'spread' of the statistical variations ... or for statisticians the variance of the standard deviation) there may be MANY groups of 100 people with zero, and SEVERAL groups of 100 people who have 4 or 5 or 10 ... way above the overall average.

For interest, let me put it another way. I heard this wonderful analogy on a program about ID.

Suppose I deal out a bridge hand. In case you don't play bridge, or some similar game, you take 52 cards, shuffle, then deal out four hands (13 in each). Now, you might look at the hands, and say, WOW, what are the chances of dealing out exactly these hands in exactly this order? And it's INCREDIBLY small.

So working backwards, it's easy to think, wow this is weird.

However, of course you have SOME hand, because you've dealt it out. It's a CERTAINTY you'll get SOME random distribution of cards.

(Of course, in real life, you don't just look at the order it's being dealt out, you get your 13 cards, rearrange, and then work out how good it is. And there are fewer very good hands, than average hands. So if you get the BEST POSSIBLE HAND, then this is rare.

However, play long enough, and you will get the occasional great hand.)

That was supposed to be "variance OR standard deviance" not variance OF the standard deviance, which doesn't mean much.

something else to consider is the ages of other folks on your friendslist. the lj stats page partway down technically only shwos the ages of people who have provided an age, and even still some of those may be inaccurate, but it's still a decent enough bunch of figures. basically, if you have only a few people on your friends list over 50 but a whole lot under, and then factor in all the various external influences beyond your control, there's a fair chance that someone on your list dying will fall into the untder-50 category.

a possibility also coming to mind is a generational issue: weblogs aren't particularly common among the over-50 group because they're a bit of a generational thing, but folks above 50 that adapt their lives to include weblogs may be more likely to have better life-survival skills and as such may be better at taking care of their health. (totally theorizing here.)

i've had a number of lj friends passing in and out of my journal and the count has gone over a hundred a few times, but it's currently at 75. i've seen one known death (20-something-year old that overdosed) and have seen a couple of journals be deleted by people who were not in great mental health conditions, one of whom i suspect may have overdosed as well, although more likely intentionally than the other, as well as one journal Ended because the user was returning to the cultish religious group she grew up in and as such could no longer communicate with the Outside World, which is kinda like a death although also totally different.