I apologize for sounding harsh, but there have been way too many misplaced apostrophes when writing about decades. From television to billboards to even print journalism, people all around the country have been exposed to it for so long, the wrong way has become commonplace.
Why are these incorrect?
The rule is to use an apostrophe to indicate numerals that are left out and add an “s” to show the plural, according to The Chicago Manual of Style and The Associated Press Stylebook.
I do not know where the “apostrophe s” came from. Traditionally, it is used to indicate possession and makes no sense here. A decade cannot have anything.
The correct way would be the following.
‘90s (with the apostrophe inserted to replace of the missing “19” of 1990)
Coming up Wednesday