Powered by NerdTools.co.uk Uptime Tracker (http://uptime.nerdtools.co.uk/) this plugin will add a widget to your sidebar that will show the percentage of availability or uptime for any website over the last 30 days.
In terms of the tracking system, checks are carried out every 5 minutes from different locations and then averages are worked out to form the overall reports from which the graph is generated and shown via an iframe.
Other reports including hourly, weekly and daily can be seen by visiting the Uptime Tracker website directly.
