Question on finding what keywords were searched in AppStore

I’m trying to find out the search terms people use for when they reach our fantasy football predictor app (https://itunes.apple.com/us/app/perfect-score-football-predictor/id908172541?ls=1&mt=8).

I have a few keywords targeted like football, predictor etc as usual. However, AppStore is such a black box that I don’t have any specific way to know what are the keywords people use to find us…

Any help would be appreciated!