1) Google has announced yesterday that it won’t be accepting flash-based ads after the end of June 2016. From 2017 onwards all ads will have to be coded in HTML5.
2)Flash is now widely regarded as a performance-hampering safety hazard and more and more companies are turning their back on what was once the industry standard.
3) Citing security concerns, Mozilla recently disabled the Flash plugin in its Firefox browser by default;
4) Amazon has banned it from its advertising network and other companies are following suite.
5) In January 2016, just 18 percent of websites in the Alexa Top 10,000 used Flash, down from almost 50 percent four years earlier.
You will find more statistics at Statista
Source : Statista