Pikka: I know that it shows up in a lot of the data series. I also know that it stems from the basically the same roots so that is hardly surprising.
Sure we cannot, because the data does not allow, assume that it is a regular cycle beyond the two cycles that we can see. We also cannot assume that it is not a continuous cycle either.
We do know that there are very long cycles in the data. We cannot assume they do not exist either (just because it is convenient to do so).
I rather suspect that the next few years may well make it more difficult to ignore these natural cycles in the data.
I have already made a prediction (based on natural cycles) that next year’s UAH figures will be lower on average than this years. Time will prove or disprove that.