Combo x-y chart and background areas for blood pressure chart

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Hi All:
I'm doing a blood pressure chart, which consists of simple x-pairs (for
systolic and diastolic, natch). Behind these pairs I'd like coloured
areas (rectangles) representing the bounds for normal, hypertensive,
etc regions. Like so:

|
| *
|____________________________________
| * |
| |
|______________________________ |
| | |
| * | |
| | |
| * | |
______________________________________

Any suggestions?
Thanks for your time,
Garry