【How-to】Is it 5 years experience or 5 years experience

When I was growing up, apostrophes were used much more commonly to form plurals–in expressions such as VIP’s, 1940’s, and in the 30’s (temperature). But now all those are rendered without the apostrophe, as VIPs, 1940s, and 30s. In your writing, you will almost never need an apostrophe to form a plural.