This graph shows the filling rate of a conference room (entries minus exits). By examining the graph we can get information. For example, it looks like the ceremony begun at 15:30, but in the morning, from 11:30 to 12:30, there were already 17 people getting it ready. The ceremony was finished by 17:30, and 162 people attended. 7 people left early. Perhaps they didn't like it, or maybe they were in a rush.