Depends on how you measure it. One way is the way you cited, another is number of active users -- and they're roughly equal as of last year (GMail has become much more popular). Yahoo currently had 1 billion as of February last year whereas GMail had the same at the same time (Feb 2016).
BTW- Your sig is from Good Omens correct? Haven't read that in a decade -- I'm thinking I should reread it.