Legacy Cumulus 1 release 1.9.4 (build 1099) - 28 November 2014
(a patch is available for 1.9.4 build 1099 that extends the date range of drop-down menus to 2030)
Download the Software (Cumulus MX / Cumulus 1 and other related items) from the Wiki
Sorry, but it's not saved in the log files. The peak daily figure, all-time high etc are saved, but not the individual values. It's written to realtime.txt and there's a web tag, so you could store it yourself if you wanted (e.g. using an SQL database). The rainfall counter, from which the 'last hour' figure is calculated, is in the monthly logs, so you could also calculate it from those figures.