Where is the evidence for the claim that they happened systemically 3 years ago?
Where do you see the word systemic?
And once again, your question could be easily answered with Google. Seeing as how you’re the one that came in sprouting completely incorrect information that would have been easily avoided had you just bothered to skim the Wikipedia article on the topic, which would also have answered this particular question, I humbly request that you DYOR.