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 w

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.