So you have completely moved to GMail and think Yahoo! mail is a thing of the past. Even I had a similar feeling that GMail is now the most widely used web mail service, but only till I came across some statistics published by Hitwise according to which Yahoo! Mail is still the most widely used web mail (e-mail) service around the world.
The chart above shows the most visited websites across the world and their percentage of the entire world's internet traffic. You can clearly see Yahoo! Mail is at #4 and Windows Live Mail (formerly Hotmail) is at #8. It is followed by GMail at #9.
However, we have also noticed an increasing trend in the traffic stats of GMail.com whereas Yahoo! Mail and Windows Live Mail show a decreasing traffic trend. These are signs that GMail will definitely surpass Yahoo! Mail as the most widely used e-mail services.