I did not know, but a reader of my website found a site through a friend of his:
Scroll down to the line under the section heading "Top 20 of Whole Market".
There is always the question of accuracy of advance-decline data, because different sources differ widely depending on their (usually undisclosed) methodology. I checked the data from this source for Friday July 9 2004 against my own calculations. The data shown on the site was: 395 - 371 = +24.
This is quite close to my calculations which show 406 - 389 = +17.