I’d seen pillow graphs before (my introduction was SequioaView, the disk-space analysis tool) but I’d never seen them organised into a circle, with such organic structuring – I’m not sure it conveys as much information as the cubic pillow map, but it feels more immediate and natural.

The addition of colour to convey change adds an extra dimension, particularly with that Tuftesque colour palette, but shows only a relative snapshot in time. It would be nice to see this animated, adding a ‘year’ slider to reallocate space as the year changed and showing absolute percentages, and colour being used to emphasise the relative differences.