I am wondering which fraction of the Indian satellites are still in service after 40 years

No idea, the space graveyard of dead satellites is growing larger and larger. I guess I could also try to look it up, or knock on the door of one of my corridor neighbours who works with ESAs "Clean Space" initiative which maps space junk, among other things :P

And the second question would be how this compares with a country like the US, or with Europe.

That's a great idea for a post by the way. Thanks! :)