Why don't you create a poll for this question? for type of this question, you might get more answers with Yes or No only.
The best way to know how many percentages of websites are using DSL out there is using Google. try to find with a keyword and see Top 100 results. There are how many sites are using certificates and you will got the answers for your questions.
Hi. Today every site need SSL. If your site dont have SSL, Chrome writes in the address bar that the connection is not secure, Firefox warns users that it is better don't enter authorization data. Which user will like it? Btw, nowadays, with free SSL like Let's encrypt, installing a certificate does not require any costs and takes several minutes.