From email "I have always missed the simple ability to view the stats in percentages (as a third column). Most of the time, the percentage (let's say the percentage of mobile users as an example) is much more useful than the absolute numbers."

This would be a simple yet very useful add to Piwik.
Some challenges are:

• do we display % visits, % unique visitors or % pages? not obvious, even though % visits is the most commonly useful.
• do we add a new column in all widgets (in dashboard), or only in the main reports (when clicking on the menu)?
  Adding a new column in all widgets is a 'major' presentation change, but maybe worth it.
• Add % visits, normalized data, in the Row Evolution report, useful to compare eg. browser usage share Show normalized visit stats in RowEvolution #3729