I remember it well. We had sheets of red and black numbers and each month carefully cut out the required digits and pasted them on the chart.
That congregation was about the same size as ours, just shows how much effort was put in and how much literature placed.
Some years prior to this (1950's) we rented our KH so the chart was mounted on a pole, rolled up at the end of the meeting and taken away until the next meeting.
George