For restaurants and other bricks-and-mortar businesses, it’s common to see the year of establishment right on the building. It’s much rarer to see the number of years in business because the signage would need to be updated every single year.
In other words, the signage is “evergreen” because it is always up to date.
However, I see lots of websites, especially the “about” page, and other business copy that is obviously dated. For instance, they say they have been in business for five years but other numbers elsewhere don’t fit within this timeline.
Or they say they have been in business for five years but the page shows a copyright of 2009. So if it’s now 2011, does that mean they have been in business for five years or is it now seven years?
And then there’s the business cards that should be tossed and reordered every 12 months.
There’s a simple remedy to this challenge. When you are writing about an ongoing situation, always write the date on which it began, not the number of years. This way it will last forever and will never be incorrect.
The one exception is a completed action that will not reoccur. For instance, “serving in the Army in Vietnam for 3 years” works.
Make this a habit and your life will be easier in this small respect, assuming you care about details.