Over the past one and a half years, Stack Overflow has lost around 50% of its traffic. This decline is similarly reflected in site usage, with approximately a 50% decrease in the number of questions and answers, as well as the number of votes these posts receive.
The charts below show the usage represented by a moving average of 49 days.
What happened?
Mostly it seemed to be people who didn’t know what they were talking about answering questions badly in an attempt to win points, presumably in the belief that this would bolster their resume somehow. And people who can’t tell a good answer from a bad one voting on the answers.