As of July 2022, only 55% of sites have secure SSL implementations (configuration errors and renegotiation vulnerabilities seem to drive the 45% who are insecure). - SSL Pulse, Qualys SSL Labs - a monthly scan of security issues in SSL implementations across the top 150k Alexa sites (https://www.ssllabs.com/ssl-pulse/). Methodology (https://github.com/ssllabs/research/wiki/SSL-Server-Rating-G...).