w3techs.com SSL Certificate Authoritities usage trend stats is very insightful Historical quarterly trends in the usage of SSL certificate authorities, June 2016 Basically Letsencrypt via IdenTrust CA has grown to rank 5th largest SSL CA with 1.5% market share but it has done so without taking any or very little market share away from the other commercial SSL CAs. Instead Let's Encrypt has eaten into the previously never used HTTPS/SSL Certificate market share if you see from the historic usage trends. Never used SSL cert market share dropped from 41.4% to 32%. All SSL CAs' respective market shares rose over the past 14 months. There's still a huge market of potential customers out there = 32+45.9+0.3+0.2 = ~78.4% to capture !