Many people – alas – think that apostrophes are random decorations in words. Nope! Those apostrophes signify an “of” relationship. So:
car of Don = Don’s car
job of Chris = Chris’ job or Chris’s job (you’re allowed to add another “s”).
Did you notice that I said “of” and not “ownership”? That’s why there’s an apostrophe in “New Year’s Eve”: it’s the Eve of the New Year. (New Year’s Day works the same way: Day of the New Year.)
The apostrophe always follows the last letter of the original word or name. That’s why it’s Don‘s car but Chris‘s job (or, as I prefer to write it, “Chris’ job.” (You can practice using apostrophes here.)
Some self-proclaimed but mistaken grammar experts may try to tell you that apostrophes have to be reserved for actual ownership. According to them, you can’t write “the dog’s leash” or “a week’s pay.” I once heard an uninformed expert argue that expressions like “the tree’s bark” and “the building’s age” were new (and suspect) usages.
Nope again. Take a look at the lyrics to “The Star-Spangled Banner,” which dates back to 1814. The first stanza has three “of” usages with apostrophes:
the dawn’s early light (early light of dawn)
twilight’s last gleaming (last gleaming of twilight)
rocket’s red glare (red glare of the rocket)
Best wishes for 2018!