A guide for people making the decision for the first time.
Ask around and you will get a different answer every time, so here is the short version.
The exceptions
The exceptions matter more than the rule, and there are three of them. The figures move about, but the direction has been the same for three years.
Where to go from here
Nobody is required to explain this to you, which is half the problem. The figures move about, but the direction has been the same for three years.
Whatever you decide, write down why. The reasoning is the part you forget.