I took the extra two minutes of liberty to
find out.
It seems the cartoons were in regular circulation up until 1966, where the serilaiziation stutter-stoped for a few decades, when two new cartoons were produced in 1979 and 1980, and then it later in 1994, up until the "new generation" (re:
ick) was re-started in the 2000s.
I'm not sure which episode you'd deem the "official" end of the sries as we know it; it's between three, I think:
The Wild Chase (1965),
Sugar and Spies (1966),
Soup or Sonic (1980)