You shouldn't split the GB software sales evenly in three generations.
267 million GB games were sold in FY3/1998 and above, so ~300 million GB games were sold in the N64 era.
The GB software sales before the SNES launch are probably benign, so I would count ~200 million GB games to the SNES era and ~300 million GB games to the N64 era.
N64 plus GB = 524 mil
SNES plus GB = 583 mil
NES = 500 mil
Thank you for that info, and this goes to further show what Nintendo's actual baseline is for software sales with combined platforms of each respective generation. With a much more steady baseline, it highlights just how much of an anomaly the Wii and DS generation truly was as well.