curl progress - only show percentage

Two modifiers might help, although neither are exact: --silent will suppress all updates and --progress-bar will show a progress bar only.

Edit: One option to make things easier would be to make a wrapper using Expect to simplify the output to your shell script or whatever is listening to curl.

Does the parameter -# solve your problem?

-#/--progress-bar

Make curl display progress information as a progress bar instead of the default statistics.

From here.

You might want to try the -# option.

It shows a simple progress bar and percentage downloaded.