w3schools.com reports numbers based on its log files (i'd say the visitors of this site represent a specialized subsegment of total Internet community, from which it's hard to make a generalization about an average Internet user).
I tend to think that numbers reported by netmarketshare.com (which show that in 2018 Windows 7 has still been the most widely used OS) are more reliable:
https://netmarketshare.com/operating-system-market-share.aspx?options=%7B%22filter%22%3A%7B%22%24and%22%3A%5B%7B%22deviceType%22%3A%7B%22%24in%22%3A%5B%22Desktop%2Flaptop%22%5D%7D%7D%5D%7D%2C%22dateLabel%22%3A%22Trend%22%2C%22attributes%22%3A%22share%22%2C%22group%22%3A%22platformVersion%22%2C%22sort%22%3A%7B%22share%22%3A-1%7D%2C%22id%22%3A%22platformsDesktopVersions%22%2C%22dateInterval%22%3A%22Monthly%22%2C%22dateStart%22%3A%222018-01%22%2C%22dateEnd%22%3A%222018-12%22%2C%22segments%22%3A%22-1000%22%7D