Figure 11 shows that the resolvers that account for 50% of theIPv6 ingress set have relatively close number of IPv4 and IPv6egress addresses; the left 50% resolvers have more IPv4 egress IPaddresses than IPv6 egress IP addresse
Only Figure 12 shows that this is indeed the distribution (for 99%)
Otherwise, I think that's only one possible distribution matching Figure 11. And still, like the author's mentioned analysis of Figure 9, under assumption of equal distribution.
under the premise of resolverswith the same proportion
"Under premise of equal distribution (of both groups: IPv4 and IPv6)" - Interesting wording and probably the only one you can make from an ECDF graph.
Figure 10 actually conveniently shows that this conclusion (under the simplifying assumption) is false, as ~1% resolvers have >50% IPv6-to-IPv4 ratio (p99 = 0.5).
Figure 9
Description: The graph shows that resolvers overall have more IPv4 than IPv6 egress IP addresses. - ~99% of resolvers have about at most 10 IPv6 addresses only. - The top 20% of resolvers with most IPv4 egress addresses have >80 IPv4 egress addresses.