How to read collection values?

A beginners question here:  When I'm on the “My Collection” page, it has stats at the bottom.  When I look at the value list, it shows “My Values” and “Estimate”.  Next to each heading is a dollar value and underneath it says for a certain percentage of my items.  What do these numbers refer to?

My values is the summation of buying values you've entered while adding items to your collection.
The estimate is the summation of Numista values (which are calculated from user entered buying values, entered auction results and sometimes metal values) if one exists for the given item and grade.
The percentages should be self-explanatory.

-hope that makes things a bit clearer.