Another option would be a stacked area graph like this (the one on the right)

http://www.asymco.com/wp-content/uploads/2013/06/Screen-Shot...

Wow. Stacked area charts are so bad at conveying information efficiently or honestly - this one would be a good parody if it wasn't presumably an honest attempt.

RE: dishonesty, see for example http://www.leancrew.com/all-this/2011/11/i-hate-stacked-area...

RE: inefficiency, note how bad the trend lines become near the top as the noise accumulates from the curves below. e.g. the galaxy tab curve on the left. I am reduced to visually converting areas into numbers (something humans are quite bad at) and searching for the previous data point, etc.

The one major thing this chart has going for it, though, is that it makes me want to play some old school video games.

See also: http://www.edwardtufte.com/tufte/books_vdqi

"Here’s a fictitious example to show what I’m talking about."

Yes, the author's fictitious example sucks.

The chart I linked shows the data points as discrete, so it's actually the stacked column chart the author claims to prefer and eliminates the confusion between height and thickness (that said, I don't object violently to that specific issue since I know how to read the charts).

Why convert curves to numbers? If you just wanted numbers read tabular data.

Tufte uses the equivalent of stacked area charts in one of his most famous examples (Napoleon's attack on Russia). Is it the width or the height of the bar that connotes the strength of the army?

http://www.google.com/imgres?imgurl=http://cartographia.file...

Tufte's great. You can quote him on both sides of most arguments. Displaying information well requires judgment, not just a bunch of rules.

The graph you linked is discrete only by technicality (all data samples are discrete, after all.) Compare how yours is 19 time slices squished together into a width (normalized for aspect ratio) almost half the size of the one I linked, which is 6 data points with adequate white-space.

Please note that in the (excellent) Napoleon chart, cross sectional thickness is used to convey the size of the army. Not only is this intuitive, but it is masterfully hinted by the way the line shrinks. Stacked area charts (as detailed in the article I linked) however are unintuitive - a slowly increasing trend stacked on a faster increasing trend will appear to decrease - this is very undesirable.

The chart you linked seems to want to say "The PC(+tablet) market is increasing, but Window's user base is stagnant". Either unstack the data or throw away/combine the irrelevant data. If you want to compare the Galaxy Tab to other Android tablets (as this chart seems to want to do as well) you will need a better chart or a second chart. The top of left chart is visual noise.

Agreed that would be better, thanks. I'll try that next time.

Given that ultimate volumes aren't relevant, I think a stacked line chart (with colours for each language) might be appropriate. You might need to bunch together the least popular languages as "other" to get that to work though.

What struck me however was how little the popularity of the largest languages changed in terms of their question frequency.