How Many NEST Cams / Drop Cams Are Out There?

I've tried googling, but no dice. Any idea how many nest/drop cams are in use?

In 2014, during a techcrunch talk, the founder said that dropcam upload more videos to Amazon servers then Youtube.

Rough guess: 200,000 - 600,000. I am assuming total of ~$50 million worth of hardware sold total at ~$130 each (after factoring in lower cost early units, margin for resellers like Amazon, etc.).

In the greater scheme of the overall IP camera market, that's fairly small but it's disproportionately sold to wealthy techies who talk.