NPM by numbers is a visualization of data gathered from NPM.js. Specifically, it is an overview of the packages that existed in NPM as of Sept 22nd, 2014. This tool gathers information about version numbers, dependents, package age, last update dates, maintainer count and so on. You can explore how the entire NPM ecosystem looks like across those variables.
You can read more about Npm By Numbers on this bocoup blog post.