Here's one way:
http://www.arouet.net/archives/2004/08/show_the_datas.php
You have to scroll down a bit, the page's layout is a little funny.
If you don't care about the first date also showing, here's another way
which may be marginally easier:
Have your dates in descending order in the sheet.
Create your chart.
Go to Chart menu > Chart Options > Axes, change Category Axis to Category.
Double click the X axis, Scale tab, select Categories in Reverse Order and
if desired Value Axis Crosses at Maximum Category.
- Jon