The presentation is from... long time ago :-) Now they serve to everyone over IPv4 and IPv6 and these stats are the actual IPv4 requests vs. IPv6 requests that

The presentation is from... long time ago :-) Now they serve to everyone over IPv4 and IPv6 and these stats are the actual IPv4 requests vs. IPv6 requests that they get, not some projected number. On address selection: Safari uses Apple API which has a proprietary mechanism for determining whether IPv4 or IPv6 gives a better user experience. You can approximate this as an RTT race between IPv4 and IPv6 connection (thus, somewhat of a flavour of what we describe in RFC6555). Firefox/Chrome give a small headstart (~150-300ms) to IPv6. IE strongly prefers IPv6, except if a particular MS-hosted IPv6 site is not reachable, then it strongly prefers IPv4.