Has scientific output in photosynthesis research peaked?

I have bookmarked search queries for "photosystem", "cyanobacteria", and "photosynthesis" on the pubmed database to keep up to date with the literature. I have done that for quite a few years now and I have noted a trend in the "results per year" box that the search usually shows, on the right corner...

It looks like scientific output in photosynthesis research has peaked. See the graph below that shows the number of papers found for each keyword per year. The trend is clear:

In the years 2000 and 2001 there was a big rise in the number of publications on "photosynthesis" and "cyanobacteria"... and then it kept increasing non-stop. There is a tiny slow-down around the 2008 economic crisis, but since 2015/2016 the output reached plateau. 

Is this reflecting the economy?

I don't think it is just photosynthesis research. Have a look at this, using "mice", "cancer", and "neuron" as search queries:

You can see similar trends... What does this mean? Have we reached the maximum capacity of our intellectual potential as humans?

Well, I do not think so... while the number of PhD graduates and postdocs has increased massively the number of tenure-track positions at universities and other academic institutions has not change at all for decades. So, I don't think it has anything to do with capacity for output, but a reflection of the amount of cash that is invested in research.

It is a problematic trend, however, if one is counting with scientific innovations to overcome the greatest challenge we have ever faced: climate change!

Let me know what you think.