[Freak_NL]

Hmm, tough question. You might get a more representative number by adjusting a bit for changeset size, although I'm not sure if this is easily available in bulk data. It would give a more reliable metric at least.

On the whole it's hard to measure the impact someone has on the project though. Some people tirelessly keep the documentation wiki up-to-date, or paint bikesheds on the tagging mailinglist. Some fix bugs in JOSM, Carto, and anywhere that comes along their path. Some manage to get governments to agree to license valuable data sources for use in OSM (this one is potentially huge), and again others write JOSM plugins to unlock such data or to scratch a common itch improving the efficiency of hundreds of mappers.¹

There is one mapper in the Netherlands who welcomes all new mappers starting of in the Netherlands: that's an invaluable service hard to quantify in data!

1: Or in my case, build a plugin that a dozen or so folk seem to use once a month. :P