Sudden jump to 79 million users online

On Monday Steven Schoen from Hawaii, one of my remaining “real” blog readers (I almost don’t post the last months!) warned me that « suddenly » the Skype concurrent users online reached 78,539,279 around 18h00 GMT. Yesterday I saw concurrent users online go above 79 million, also around 18h GMT.

Strange, because the last months there was a downward trend, from about 60 million at peak time in the beginning of the year, to about 56 million at peak time last week.

Why this sudden growth of the number, around 20 million more, one third more? Certainly not a sudden increase of the users, I don't believe this, probably some technical reason:

Probably Skype changed their algorithm to estimate the concurrent users online. But this is a guess!

Question: can we trust this number? I doubt about it, as does Steven!