Leaderboard called "100 days performance score".
Score depend on items sold and its difficulty in the last 100 ingame days.
The more items sold and the more they are difficult the more score you will get.
Detailed in game report will be added soon about this performance score.
http://steamcommunity.com/stats/514290/leaderboards/1490027/
To submit your best saved game score,just load the game and leave it running for 100 ingame days.