I have written previously about the error of putting apostrophes into words that end in S but are not possessive: My cat’s chase each other through the house at high speed’s. Cats and speeds are merely plurals and do not take apostrophes since no ownership is shown.
Here are three other instances when an apostrophe is not needed:
1. When referring to decades: the 1990s
2. When referring to temperatures: highs in the mid-70s
3. When using abbreviations that are plural: 12 CPAs, two BMWs
Every time you want to use an apostrophe, take a good look and see if it really is in a possessive word or in a contraction. If not, delete it.