The height and width of the graph are configurable. By default I left it at 31px high, which allows for a maximum of 1 post per day. The width is based on the number of months, which by default is 12*3 i.e. 36 months or 3 years worth of data.
Here's the raw result followed by what it looks like on my blog itself.
This is the code that makes it possible...
That php file will generate the graph image, now to use it, simply make an img element in the html.