additive/stacked line graphs

[Elmarie]

I am trying to graph columns of data representing energy use, broken up by source of the energy. My graph should have 3 lines, each representing a different source of the total energy requirement. One is a fixed amount each month (flat line), the other two lines vary by hour. I need for the fixed input value to be the "base" and the other two values appearing as additive to that base. My boss did the graphs previously and his show the fluctuating lines as additive to the base (fixed value) line. For instance, if the fixed value is 3.5 mW for every hour of the month and the second source of power ranges from 1.1-1.6 mW every hour and the third source ranges from 1.3 - 2.0 mW every hour, then the graph should show the fixed line at 3.5 and the range of the first fluctuating line would be at 4.6 - 5.1 (1.1-1.6 added to the fixed 3.5) and the second fluctuating line would be graphed at 5.9-7.1 (1.3-2.0 added to the base of 3.5 and the values from the first fluctuating line). I can't figure out how he did it and he doesn't remember either! I have tried copying all the selection data exactly as it appears on his chart, but mine just turn out as graphs of the individual column values, nothing additive. HELP!