Kyle McDonald wrote a Python script that dumps basic statistics information from GitHub for all the Deep Learning Toolkit projects that are included in this list.
This Reddit comment, from November 10, 2015, describes the script, and summarises the results:
From 2010-2015 a new toolkit was released every 47 days. This year, it's every 22 days.
The Reddit comment, and the toolkit list is maintained by a user called kcimc, which is presumably the same Kyle McDonald as the script writer.
This is a count of the releases, not a count of the total number of toolkits. So, a new release of a toolkit occurred, not necessarily the release of a new (novel) toolkit.
This is a standard English idiom that means that on average there was a release for every 22 days. It does not imply there was a release exactly on day 22, 44, 66, etc.
While this wasn't published in a peer-reviewed source, the claim is fairly prosaic, and it isn't hard to reproduce the results by hand, so it seems reasonable to tentatively accept the claim, at least for the first 10 months of 2015.