Seems, the probability of success (being granted asylum) is higher when doing it affirmatively than through the courts. I think most of us make the mistake of not finding a lawyer in the affirmative process...big mistake. Those who get lawyers, submit a mountain of evidence to the Asylum officer, win.
I couldn't find data on the total number of cases: Just saying that in 2017 16045 people got asylum affirmatively doesn't help much. We want to know, how much were the denials/referral to court out of the total pool?