Be aware that this statistics is only about the top 40.000, if you extrapolate the graph, you see 50% outdated software for the top 10 million.
As this takes a lot of resources, do you find it usefull? Or do you think the 40.000 is already representative?
Small stat: At the moment we are scanning at an average rate of 2000 sites / hour. So average of 0.03s for each site. Making the stats page has definitely helped us to test/increase our performance.