This is not always exactly true if you dig into the details - for example, something like 20% of fathers get custody - but it's something like 90% of fathers who try to get custody get some.
“Some”?
Anything less than fifty percent is state sponsored kidnapping.
How many don't even try though because them assume it is hopeless. Some custody includes things like 1 weekend a month - if that is all you get it wasn't really worth the bother.