In January 2008, Naomi Robbins wrote an
excellent article on how to display the evolution of seasonal data.
Jon Peltier (again ;) ) walked this road of cycle plots and panel chart
here and
here.
Finally, Charley Kyd proposed a very good tutorial on how to
create cycle plots with Excel ... a rather long way, especially in the formatting process.
My turn to propose the Sparklines alternative. It took me less than a minute to create this chart.
It consits in 12 line charts, one per month, displayed in a narrow cell.
All cells obviously share the same vertical scale.
The red and blue points represent the minimum and maximum over 12 years.
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The file is available for download
here, and requieres the add-in to be installed.