Simplify the following text for a Grade 6 native English-speaking person.
Original: These conclusions were initially supported by the American public ; however , polls conducted from 1966 to 2004 found that as many as 80 percent of Americans have suspected that there was a plot or cover-up .
Simplified: At first , the American public thought these conclusions were correct . However it is now thought that as many as 80 percent of Americans think that there was a plot or cover-up .