Hi Karen,
if you just want something random and don’t need to control the actual values, I would do this with a text-animator:
Make a text layer containing •••••••••••••••••••••••••…
Draw your trend line as a mask-line on this text layer, then enable text on Path.
Add a position animator with Wiggly textanimator (but with Wiggles per sec at 0 so it’s fixed).
Give the animator’s Position-value a bit of X and some more Y depending on how scattered you want it to be.
You can add another text animator to anim-on the dots 1 by 1 (with opacity, perhaps scale), and a third animator could be used to add random colors to the dots.