I love JMP and use it all the time. But- there are so many packages for area under a curve that are superior to JMP. Mathematica is in my opinion the very best. A good cheap contender is the free cousin of MatLab, called FreeMat

http://freemat.sourceforge.net/

However, if all you want is to connect your data points with lines, then calculate the area underneath, and if your points are all 30 units apart from each other, then the answer is simple, because each area part is a trapezoid with a horizontal base, and all the bases are 30 wide. The area under each trapezoid is then the width (30) times the average height. For two points (x1,y1), (x2,y2) that average is (y1 + y2)/2 .

Let y1 be your first point, yn your last point. The area under your plot is then

[(y1+yn)/2 + (y2 + y3 + ... + yn-1) ]*30

The first and last points are included only once in the area calculations, thus they need to be halved. The others are in there twice, so you just sum them up.

Re Gompertz, any nonlinear fitting is dependent on starting values. JMP seems to do a great job with its default starting values, so give it a try. You might not get convergence according to the JMP stopping rule, so just choose to accept the current values if the parameters are stable (unchanging) enough. Or try resetting, and selecting the option of numeric derivatives. That sometimes will help. Good luck.