Users are also able to enter "messages" associated with certain dates.  I'd like to display these messages in the x-axis.  Ideally, I'd like to show a "M" or something like it (for Message) in the x-axis; when you hover over the "M", I'd like for it to show the message that the user has saved.  Is there any way to do this?  Currently, I am just plotting points below 0, but I'd really prefer to put them below the x-axis so I don't see negative numbers in the scale on the y-axis.

Any thoughts are appreciated.