I’ve done traffic counts using FlightAware and comparing to what I see on my LNM map for the immediate radius of about 50NM around my plane. The best we can expect to see in sim is about 20%. Typically, we see about 5-10% at most.
I do think there’s some irregularity in how traffic is displayed in different regions though. In certain parts of the US (typically in south Florida), I’ll see 15-20% at times. AT TIMES… Other areas like Europe, I’m lucky to see 5%.