How to find total number of player accounts

We don't currently provide aggregated info across all players like this, as described in the other post where you were asking about this (https://community.playfab.com/questions/9847/how-to-find-total-number-of-player-accounts.html). For more advanced analysis of players, like getting percentages of the player base above/below the current player's score, your best bet is to use PlayStream to collect the data in realtime for all player statistic updates, in order to maintain the record of total number of players and score "spread" in your own server/data table - which you could then provide access to from Cloud Script via a Web API.