Here’s an interactive collection of the world’s biggest data breaches. It goes back to 2004, where about 92,000,000 email addresses and screen names were stolen by an AOL employee, and covers most of the major events up until and including 2016. There are a few ways to filter the data and change the representation.
Overall, should give you a pretty good idea of how safe and secure your online data is. Oh, and how private it is too.