Last I checked, IE11 is the last official holdout (with bugfixes and support) and it has less than 5% marketshare. That gives ES6 somewhere close to 95% markets

Last I checked, IE11 is the last official holdout (with bugfixes and support) and it has less than 5% marketshare. That gives ES6 somewhere close to 95% marketshare for users that aren't running 3-6 year old insecure and outdated browsers.