Ah, you did the same thing I did.

If you make it to ISO_8, you get redirected to this page, which really cuts the browsing time down: https://en.wikipedia.org/wiki/List_of_International_Organiza...

It's probably worth pointing out here that there is a navbox, and he could have been using that; you'll notice it doesn't include a link for ISO 8.

The time gap is also interesting: ISO 1 was was adopted in 1951, and ISO 2 in 1973. Thereafter they seem to have become much more regular.