After a little research, I would say that the absorption rate is around 60-70%.
From Big Cat:
"The injection is naturally regarded as better. Its an enanthate ester which is quite long-acting and only needs to be injected once a week in doses of 300-600 mg. Because it by-passes hepatic breakdown on the first pass, it also has a higher survival rate. The orals are a lot less handy, but often preferred by bodybuilders who are afraid of needles or who are already taking one or more injectable compounds. The tabs are in a short-lived acetate form, meaning that doses of 100-150 mg per day are needed, split over 2 or 3 doses, making the tabs quite inconvenient for use."