The numbers on the graph reflect how many searches have been done for a particular term, relative to the total number of searches done on Google over time. See Google Insights results for Drupal.
Regional Drupal interest by country. Google uses the term 'search volume index' for these heatmaps, meaning that they normalized the data by the total traffic from each respective region. In other words, just because two regions show the same percentage for a particular term doesn't mean that their absolute search volumes are the same. See Google Insights results for Drupal.
The top search on Drupal -- great for marketing people. Breakout means that the search term has experienced a change in growth greater than 5000%. See Google Insights results for Drupal.
