How to make an Excel to caculate the number based on a given date and year?

Dear Excel Gods,

I run a small business, and my policy is to give an additional vacation to employees every year.

However, since the hired date/year is different for everyone, I realize it won't be fair unless I count their annual increase by the actual date.
So I'd like to make a chart, that automatically calculates the annual increase, which goes up by 1 every time they have reached a whole year, based on the given hired date.

Is there a way to do this?

I know Excel can do A LOT, but I was also wondering if there is a way that somehow I can be notified with formula by some kind of color changing, I don't know, I'd be happy to be able to do just the first thing I asekd.

Thanks!!

Vacation.xlsx

Thank you!