Google has recently published a report about the Web, which includes a lot of interesting stats. The results were obtained from a sample of 4.2 billion web pages indexed by Google.
"The average web page takes up 320 KB on the wire (Google took into account the embedded resources such as images, scripts and stylesheets). Only two-thirds of the compressible material on a page is actually compressed. In 80% of pages, 10 or more resources are loaded from a single host."
The average number of images per page is 29.39 and the average size of all the images from a page is 205.99 KB. A web page includes an average of 7.09 external scripts and 3.22 external stylesheets. The average size of the scripts is 57.98 KB and the size of the stylesheets is 18.72 KB. Google also found that only 17 million pages from the sample use SSL (about 0.4%).
Urs Hölzle, Google's Senior Vice President of Operation, said that the average web page takes 4.9 seconds to load and it makes 44 calls to different resources. "Speed matters. The average web page isn't just big, it's complicated. Web pages aren't just HTML. A web page is a big ensemble of things, some of which must load serially," said Urs Hölzle.