It is absolutely 80%+. The majority of the time, it is a company looking to sponsor an H1B for a role or they have an H1B in the role who they want to sponsor for PERM status (Green Card) and the law requires them to post the job to prove there are no Americans available. The next most common reason is they have identified an internal candidate for the role but corporate policy requires all jobs to be posted externally to show they are looking for the best person. The next most common reason is HR conducting market research on compensation. In all cases, there is no intent to actually fill the role with an external hire.