Let’s take one example to understand the outer ring.
1) The historic figure has 3 children, say C1, C2, C3 (innermost colored circle)
2) Let’s focus on C3 (Blue)
3) C3 has 4 descendants, out of whom 3 are still alive. 1 is not (middle colored circle)
4) Let’s call these 4 descendants A,B,C, and D. A is the left most (alive), B is dead, C and D are alive.
5) A has 2 descendants. both of whom are alive (2/2)
6) B is not alive now. But he/she has 4 descendants all of whom are alive (4/4)
7) And so on.
Outer ring -> Consider the person in the ring adjacent to outer ring.
The ratio given is number of living descendants of this person/total number of descendants of this person.