Ur info is correct. Pregnancy rate of iui is just slightly higher than normal pregnancy, but it is still a treatment for ppl with infertility since the chance of having no babies after having normal sex life for a year is less than 10%.
And the successful rate for iui is cumulative... i.e. the more attempts u try, the higher chance you will bingo. That's why most doctors will recommend Ivf if u fail iui for more than 3 times, i.e. 60% chance of success but still fail.... So Ivf may be better choice then.