Oh but there are

That is a very easy crime stat to obtain if you meant to. (And yes, I probably have links, somewhere)

Kidnap + Murder of a stranger child has never passed 200 any year in US history since records began, as far as I remember.

The overwhelming majority of child disappearances are runaways. The overwhelming majority of the rest are parental / familial "kidnappings", usually in context of rather hostile divorces and many times (not always) with acquiescence of the child. "True" kidnappings are rare, and the overwhelming majority of them are for money or blackmail, so the child is not killed or sexually abused.