Figures are estimates only and based on an average of scrum times and lineouts times taken from the Edinburgh vs Cardiff Blues European Cup Quarter Final. Scrum time was calculated by recording the time taken from when the referee used his whistle to indicate a scrum, until the time the ball emerged from the scrum, or the referee blew his whistle indicating a penalty or another scrum. Lineout time was calculated by recording the time the ball left the field of play and then recording the time the ball left the hooker's hands. Full details area accessible here, but this data is created by estimating that each scrum takes 56.95 seconds and each lineout takes 23.81 seconds.
For games other than Top14 games, ESPN provides data on share of possession by teams. It is therefore possible to calculate how many minutes each time had possession of the ball during games. As we also know the points scored by each team, it is possible to caculate the speed with which teams turn possession into points. For example, if a team secures 50% of possession (equalent to 40 minutes) and scores 40 points in a game, then their rate of scoring is 1 point every 60 seconds.
All raw data courtesy of espn.com and official websites