south were. >> they all had pretty high ratings. cbs became known as the country broadcasting system. >> but in the late '60s, ratings and demographic tools improved significantly. networks are able to see the ages, the he indication level, what kind of jobs the people reviewing the shows have. >> so the more they could refine that, the more they wanted young, professional, wealthy people. >> joining "entertainment weekly." great to see you. class divisions have been highlighted in sitcoms over the years from "the beverly hill billies" to "schitts creek." why is that good for sitcoms? >> sitcoms are great for tackling all sorts of issues, you know, this series, "history