Would be interesting to compare several other stats overlaid. Last year's looks a lot like most posts are in Northern Hemisphere winter/cold. Holidays, disruptive news, and other factors can also play a part.
Nothing better to do or a distraction needed from life... go look at what's happening on the web and interact.
I doubt that anything requires blame/fixing on the part of the Cafe or that instigating rage or raves is required. One could also overlay visitor numbers instead of posts as many members are more interested in reading/learning rather than giving advice or opinions.