These charts show our luck with the blocks we have created. Sometimes it takes a little work to produce a block (lucky), sometimes it takes a lot of work (unlucky). To measure this we use the Cumulative Distribution Function (CDF). We display the CDF as a percentage. The lower the CDF value the better, with 50% being the expected average over time. The charts have 0% at the top and 100% at the bottom, to make them easier to read (higher on the chart is better). You can read more about CDF at Wikipedia.
Place the mouse pointer over a point in the chart for details about that block.