April 21 2015, Google: “we will be expanding our use of mobile-friendliness as a ranking signal”
This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results.
It is thus necessary to take the step with the changes, if we consider that on average 30 % of the visitors originally arise from the browsing by mobile responsive web site: it is interesting to think of optimizing your Web sites towards a responsive design. If you are in a situation where you have to make a revision of your Web site: it is maybe that you were badly advised in the past in your investments. Try to find a trusted advisor for your business which will be able to direct you to solutions which evolve in time.
**source: Google Webmaster Central Blog, Finding more mobile-friendly search results