I suspect it's related to Chinese New Year, as the peaks in the graph change from January to February depending on which month Chinese New Year falls into. Edi

I suspect it's related to Chinese New Year, as the peaks in the graph change from January to February depending on which month Chinese New Year falls into. Edit: ah, M0 is cash. It is traditional to give cash in red envelopes at Chinese New Year, which could be related. I'm surprised the spikes are so large though.