In other words, how long on average does a person hold the title of world’s oldest person before they die?
And to get the obvious joke about the awkward title out the way: “They only die once! Hyuk yuk yuk!”
I don’t have the answer but I think this article may be of some interest
http://customwire.ap.org/dynamic/stories/O/OBIT_OLDEST_PERSON?SITE=FLDAY&SECTION=HOME
Well, here’s a guess: This site gives a life expectancy table, supposedly from an IRS publication (?), that includes the following data:
Age Remaining Years
100 2.9
101 2.7
102 2.5
103 2.3
104 2.1
105 1.9
106 1.7
107 1.5
108 1.4
109 1.2
110 1.1
Wherever this comes from, I can’t believe there’s a lot of data points for the life expectancy of people who are ~110 years old. Nevertheless, I imagine the oldest people are in the 112-114 range, and I would assume (extrapolating a little) that these people probably have a life expectancy of a little under a year. How’s that?
Hah! Revtim , you missed one:
“On average, how often does the current world’s oldest person die?”?
Every time, buddy. Every time.
It’s a start; but to get the answer we need to know how many are in the top bracket. Actually, we need to know the top bracket of just one person!
lembranca, it was her death that got me wondering. Actually, I wonder every time I see the “oldest person dies” headline.
rimshotgdansk, I don’t think I’ve ever seen a more appropriate username! 
Here’s how you figure it out. Look at 30 years of Guiness Books of World Records, and see how often the title changes hands.
You will miss a few who died within a year, such as the most recent title-holder, but only a few. Add in one or two guys, and you have your answer.
rimshot: And you missed another! “Once.”
Ah! Good idea, Izzy. Here’s a list of the oldest living humans since 1955 (scroll down to the bottom). From Oct 24, 1955, until October 31, 2003, there were 24 people who held the title of world’s oldest human, which means that the average length of time anyone held the title was almost exactly two years. Of course, the median is less than that.
Hey looks like that’s it! Good job zut.
ZOMBIE THREAD RESURRECTION AFTER TEN YEARS:
According to this:
the answer is “Every .65 Years”.
Awesome!
Question: Did you just happen to come across this one day, or have you done nothing for the past 10 years, neglecting all other obligations, in the quest for an answer?
Now I just look at myself in the mirror and ask, what now?
Revtim, how long does the world’s youngest person hold that title? Seriously, it’s like less than a second or so on average, isn’t it?
If you were hoping this would give Revtim something to live for for the next ten years, I’m sorry to have to tell you that this is a very easily answered question. 
The World Population Clock increments by 1 in less than a second (and that’s counting attrition from deaths at the same time), so the title of World’s Youngest Human is subject to very rapid turnover.
Here’s an up-to-date list of the oldest living people since 1955:
The list is about a third of the way down.
I used to hold that title! But now, I just can’t keep up with these KIDS! Every new record hold is younger and younger. 
According to this sitethere are 4.17 births per second. so the average newborn will holod this record for just under a quarter of a second.