Thanks to Randall Munroe I've dated them to the early 1940s (left globe) and the early 1970s (right globe). If you haven't seen this Randall MunroeComic, it's pure gold:
xkcd.com/1688/large/
TrueWordsRSpoken Ron Filipkowski At least credit the strip, FFS. Randall Munroe, Randall Munroecomic. xkcd.com/1357/
Me: I cannot just spend the rest of the day rotting on the couch!
::puts a load of laundry in::
“COMPILING!”
(credit Randall Munroe)