Cumulative Line Charts

For example, to see the total amount of closed opportunities by day in the current month in a report, set amount as the Y-axis and closing day as the X-axis. The chart displays one line, with the line’s height representing the cumulative amount of closed opportunities up to and including that day. You can't see the amount for any single day—only the cumulative amount.

If the data set contains a missing (null) value, Salesforce continues the line using the previous value in the data set.