Statistics about development of average connection speed and latency over the years

Question

Are there any statistics about the development of average internet connection speed and request latency from households to major sites over the years?

I find this information very useful for ajax related software design (i.e. feasibility studies of several webapp use cases).

Answer 1

I found good statistics at http://www.netindex.com/ but only ranging back to 2008 and with no explicit latency rate measurements.