Numbers Generator Speed

In the Numbers Generator inspector, turn off Animate.

As you mouse over Value, you'll see a small diamond shape appear. With the playhead at the beginning of your project (or where the Numbers generator first appears in the timeline) click that diamond shape - it will turn yellow indicating you have set a keyframe.

Move the playhead where you want Numbers to stop counting and set the Value to 1000 (a keyframe will automatically be added since you started the first one.)

At the bottom right corner of the Motion window, click on the diamond icon to open the keyframe editor. You will see the two set keyframes and a line connecting them. Click on one of them and Command-A (select all), then right click on one of the keyframe diamonds and select > Interpolation > Bezier.

Drag out the first control point along the same axis as the starting keyframe (hold the shift key down to constrain.)

For the control point on the second one, slope it downwards about 30-45°. Something like this:

There are behaviors (Exponential) that you can use, but I think you'll find it's action unsatisfactory (half the project time will remain at 0 and then rapidly increase to the limit.)

Here's the result:

You're most welcome. You can learn a lot here.