It was IBM 347, Microsoft 360, Samsung 523. And this isn't a one-off spike.
I'm not sure what's happening here. 6K patents per year means tens of millions of dollars in filing fees alone, so it's obviously a huge investment with some kind of strategy behind it. I don't believe Samsung has suddenly built a network of research labs to rival IBM and Microsoft. It seems likely that they've just decided to become very aggressive about patenting absolutely every idea their people can think of. Over the years a lot of people have warned about what could happen if someone tried to exploit the weaknesses of the US patent system to the maximum (and the patent industry has pushed back with "don't worry, that's not happening"). It may well be happening now.
What next? Things could be very interesting. We may see US companies ramping up their patent-farming efforts to match. But I think we will also see good old-fashioned nationalism (perhaps with a racist flavour) coming to bear on the question of patent reform. Will Americans stand for the transfer of public ideas into private monopolies when it's foreigners locking things up? But if the US government starts to backpedal, and possibly even breach its WIPO commitments, then that gives cover to other countries to implement sensibly restrictive patent laws. That would be a good result.