Accessible data visualisation

Context: we have examples of just a chart. Usually they'll be in a page with other stuff. The charts and data are auto-generated and updated, so we can't supply a human-written text alternative.

Testing order:

1. Example 3: table best? after the chart? Name for button? Button or something else?
2. Example 4: alt text good? Link text good?
3. Example 7: tabs good? role? text? region?
4. Example 8: arrow keys good? role? text? region?

If there's time:

1. Example 1: alt text good?
2. Example 2: alt text good?
3. Example 5: leaving SVG text readable is bad?
4. Example 6: hiding SVG text is good?