Alun, you made me think:
If I want results, such a graph and statistics about deviations from the norm, or increase or decline,
what programming language and platform would you recommend to me?
To give you a clearer pic what I would like to research about:
This guy who focusses on swing-trades seems to compare cycles:https://swingcycles.blogspot.com/2011/03/what-cycle-analysts-are-saying-part-1.html
If I could see two charts with statistics I could then alter either the time-difference or set different times,
and maybe later even compare more than two time-spans.
Since I start from scratch I still am open to any paths.