Since the common theory is that Monsters Inc. is in the future (with time travel) this seems to line up more with the present day events, rather than time in Monstropolis. I will, however, move A Bug's Life to 2000 to fit with the calendars shown in Monsters Inc.
Perhaps numberplates are used to show the actual year in Monstropolis, but everything else lines up with the human world as a political change somewhere down the line for quality of life, and numberplates are kept in the same year as it actually is because it's more reliant on the actual year. Nevertheless, I will leave the poll open on the previous comment. I guess use a sad emoji if I should disregard the numberplate entirely