Getting data from a chart that is displayed on a website

Question

I was asked to draw a graph like this one

using Latex (more precisely, tikz and/or pgf). This would not be a problem if I had the data, but I don't. All I have is the website from where graphs can be displayed, but I don't know how to get the data from there.

I spent the day today trying to get this data, including writing to Google and using a type of software which traces the line and infers the points of a graph, such as Datathief and DigitizeIt, but I was unsuccessful. I think the latter did not work because the lines in the graph are too thin and have more than one shade of blue. Of course, I tried to improve the picture quality using Paint and Gimp but I still couldn't make it work.

I also tried using eps2pgf, a Java script which transforms eps figures into pgf code, but even that was not working for the graphs I saved using Image Capture (mac) and Print Screen (Windows), and to be honest this would be my last option since it is a "brute force approach", spitting an ugly code that you can't really improve on.

After all that I decided to start learning Python, because my supervisor, the person who asked me to draw this picture using tikz, said that there is a Python code to get data from websites like this. Now I am not even sure Python will do the job (though I am happy for the excuse to learn it) and of course it takes time to learn a new language and do something like that, so I want to know whether there is really a way to get the data from that website, using preferably Python but if not, any other method.