In the year 1950 (literally that year, not counting any following year) the longest range aircraft is 5520nm.
in the year 1960 (literally that year, not counting any following year) the longest range aircraft is 5643nm.
in the year 1970 (literally that year, not counting any following year) the longest range aircraft is 8079nm (and that aircraft becomes available literally in 1970, closest in the early 60s is in the low 6000's and in 67 we get a plane that flies 7800~ nm).