Line Chart with Accumulation up and down?

[#1]

I am looking to create a chart that shows numbers of open orders by date.

I have 3 fields for each order - order open date, order closed date and a counter. I can produce a chart that shows the numbers of orders increasing, by setting the x axis to Order Open Date. and the y axis as count(Counter) with Full Accumulation.

I would like to incorporate the Order Closed Date so that the line chart goes down as well as up, during quieter and busier periods.

Any suggestions would be welcome.

[Gysbert_Wassenaar]

That is a lot easier to do when you first generate a table with records for each day between the open and closed date for each order. See this blog post: Creating Reference Dates for Intervals

[#3]

This looks good so far, but I have 1 issue.

What if there is no ToDate, as an order is still open? Will it still count the order as open today?

[Gysbert_Wassenaar]

Generate the days until the ToDate value or if it's missing until the value of Today().