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.
The file is available for download
here, and requieres the add-in to be installed.