News source: http://www.theverge.com/2015/7/21/9011657/apple-watch-apps-tim-cook
While we don't have exact Apple Watch sales numbers, Tim Cook has given us some idea as to how well developers have embraced the wearable so far. On the Q3 revenue call, Apple's CEO confirmed that more than 8,500 third-party Apple Watch apps are available. Apple previously said the Watch launched with about 3,000 Watch-compatible apps. That's about 5,500 new apps in the three months since launch. That 8,500 figure also, however, represents less than one percent of the over 1.5 million iPhone apps now in the App Store, As for how people are using the Watch, Cook said Twitter, Line, and WeChat are some of the most-used Watch apps. Communication apps on the wrist — all of which might change after watchOS 2 enables native apps (which Cook says will be "killer") when it's released later this year.