Difference between “in progress” and “in process”

Question

When reporting on a project that is still being worked on, do you call it in progress or do you call it in process?

I have heard both, and both make sense in their own way. I want to know what both the descriptivists and prescriptivists have to say.

Answer 1

Describing a project as in process sounds pretty odd to me, but apparently the form does occur - although in progress is about 5 times more common, as this NGram clearly shows.

This chart specifically for in process of [changing, for example] strongly suggests the usage is falling out of favour.

Answer 2

What I have to say:

The writing of my project is currently in progress.

or

My project is currently in the process of being written.