Bitcoin Node Software 2017-03-23 (%93.22 on Core) Lukejr tool

The methodology behind this is that you run some nodes and see who connects to you, rather than scanning the network looking for nodes with open ports. This results in many more nodes (because many nodes don't have open ports) and a different distribution, in part because people haven't gotten around to trying to manipulate this yet, and in part because this includes more "normal users" who are just running a full node for personal use.
Full nodes with closed ports are still full nodes, and still contribute in the most important way: by economically rejecting counterfeit BTC.

Here is the tool http://luke.dashjr.org/programs/bitcoin/files/charts/software.html