How many operational vehicles are still up there, sending back useful data?
How many are up there that are functionally dead?
How many didn’t make it (burned up on entry, flew off into space because of bad calculations, etc.)?
After hours of studying your question, I stumbled upon the idea of googling “Mars Exploration Spacecraft” and this was the first thing on the list:
Since your prior thread on the subject in 2009, the only new piece of human-made hardware to get to the surface of Mars has been the Curiosity rover. The Spirit rover died in 2011, but Opportunity is still going (10 years after its predicted lifespan!). So as was the case in 2009, there are two working robots on Mars; one new working one has arrived, and one previously working one has died. The total, then, is 8-10 man-made objects that have successfully landed, plus assorted other man-made debris.
Since 2009, there have also been two new orbiters (one from NASA, one from ISRO) and a flyby on the way to Vesta, but I assume that you’re not as interested in those.