The ROI is the same for everyone as it is a %. If you are asking how high is the ROI, you can go look through each of the daily posts. The ROI on average is 30%, but if SBD prices go up, so will your ROI, if the go down ROI does as well.
To give an idea, SBD price is currently $3 per SBD. If this goes up to $6, the ROI goes to 60%, if it goes to $2, the ROI goes to 20%. For every $1 the SBD price is, the ROI is approximately 10%.