Left-to-right. It's like a series of staggered bars one next to another - http://epmxperts.files.wordpress.com/2011/01/monthly-graph.png http://epmxperts.files

Left-to-right. It's like a series of staggered bars one next to another - http://epmxperts.files.wordpress.com/2011/01/monthly-graph.png http://epmxperts.files.wordpress.com/2011/01/monthly-graph.p... - with two differences: 1) It's continuous, rather than a series of discrete bars. (The linked bar chart could also be continuous, especially if they had that granularity of data. But you could try visually faking it by just connecting the bars into a similar effect.) 2) It represents market share, not absolute volume, so always adds up to 100%. Each point along the X axis contains the same information as a pie chart would at that date, showing current market share. Overall the effect is that you can track the 'shape' of the componnets as you read left-to-right. This is similar to the effect of this famous chart, http://en.wikipedia.org/wiki/Charles_Joseph_Minard#Information_graphics http://en.wikipedia.org/wiki/Charles_Joseph_Minard#Informati... - where you can see the 'width' of Napoleon's army as it marched geographically. In this case the "the size of the army - providing a strong visual representation of human suffering" is the size of RIM's market share (along with everyone else's, but this is the component the title draws our attention to), providing a strong visual representation of its suffering. And you can actually read left-to-right over time instead of having to look at it embedded in geography, as with the Napoleon campaign chart.