A grand total of 77,609 responses from WordPress users and professionals collected by Automattic between 2015 and 2017. The stats for 2015 and 2016 have been shared at the annual State of the Word address and 2017 marks the first time they have been published on WordPress News.
A few items that caught my attention at first glance:
Between 66% and 75% of WordPress users installed WordPress on their own. In other words, they were savvy enough to do it
WordPress User Survey Data for 2015-2017 is a post from CSS-Tricks