According to Wikipedia, in March 2017, Google was the most popular with over 80% of the search traffic.
Bing came in second with under 7%, and I suspect that this is as high as it is because as of January 2017 over 90% of PC type devices used Windows, and Microsoft pushes Bing.
With such a large market share of operating system usage, less than 7% of searches using Bing indicates just how unpopular this particular search engine really is.
There is one thing I like about Yahoo, that neither Bing or Google seem to do, and that is automatically open a search result in a new tab. This means that the list of my search results are still open and easy to get to. I know I can right click on a search result to open a new tab or new window, but it is easier if the site does it for me.