Autoformat numerical y-axis

[impcymru-adam-watkins]

At the moment it tries to auto-format percentage and date axis, but doesn't try to handle simple numbers.

Considerations:

• Counts
• Appropriate levels of precision
• Natural breaks
• Zero
• Thousands-seperators (",")

[impcymru-adam-watkins]

Ideally y-axis tick markers would include units where appropriate. At a minimum, the auto-formatting should retain these where they're part of the existing number format. (Note that units can be leading - e.g. "£" - as well as trailing - e.g. "cm".)

[impcymru-adam-watkins]

The Health Care Data Guide suggests:

Most of the data lies in about the middle half of the graph.