No number. These names you see on the forum are it. We're all amateurs devoted to the cause of preserving as much comics history as we can. It's hard, time consuming work and even the scanners and contributors uploading literally hundreds of files have to download 1 file at a time with the 2 minute delay between downloads.
That's the way it is.
Or, you could do your own internet searches and find umpteen sites where you can download as much, as quickly, as you want, or that your machine can cope with.
By the way, I don't know when you would find the time to read 19000 files. At 20 a day (and some of these files are really big, so it would be less), it would take 950 days minimum. I'm not sure you'd ever get through them. And unless you read a number of non-English languages, you certainly will have problems.
You do realise that there is a reader on site and when you choose a book, you can read it without downloading it? Then, if it is to your taste, you can click the download button. That way you get what really appeals to you. If you are interested in the comics, that would seem a sensible solution for you.