A couple of things pop out from this graph. First, during the last 24 years, the oldest person in the world has always been a woman. Not a big surprise there, since women live longer in general. Quite a few men have gotten past 112 years, but reaching 116 seems impossible. For female supercentenarians, reaching 114 is relatively common, and a few have even reached 116.
The second thing that catches the eye is the highest point on the graph: that's Jeanne Calment, who died in 1997 at the age of 122, making her the longest-living person ever in the world. No one else has reached even 121. Shigechiyo Izumi is missing from the graph – he was claimed to have died at the age of 120, but according to the authors, he was in fact 15 years younger.
Looks like there's a slight trend towards longer-living supercentenarians, but I'm not sure it's significant. Certainly we haven't seen anyone like Jeanne Calment in over a decade. What this graph doesn't tell us, of course, is whether the percentage of people who reach 110 years of age has changed significantly during the same time period.
For more information on aging and longevity, see these posts:
Jumping Head First into the Fountain of Youth
Aubrey de Grey Interview in Wired.com
Russian Scientist Claims to Have Found Cure for Aging
The 7 Types of Aging Damage That End up Killing You