 * Adding further information  NBC was loyal to the show throughout the 1960s and most of the  1970s, but by 1979, ratings were declining, and they demanded  changes in the format. The studio updated the visual look of the  show with a disco theme song and a fancier opening sequence. This  convinced NBC to renew the show until 1981. But the ratings did not  improve and NBC cancelled it. CBS then picked it up and featured an  even more elaborate opening sequence using then