The Responsa Project was started by the Weizmann Institute of Science, a public research university in Rehovot, Israel, and makes updates once a year between Passover and after Chanukah.
Sometimes they release an update after the holiday of Chanukah or after the holiday of Purim. In recent years (at least since version 10 in 2002), the Responsa Project has made updates available once a year, usually between the Passover and Shavuot holidays, although this varies considerably. 
