Results
Study I: dose finding
Analysis of the data on hormone concentrations after the 25- and 50-mg doses showed no difference in any of the parameters measured due to an order effect; hence, the data were grouped for analysis by dose. The 25- and 50-mg doses of daily exemestane had comparable effects in suppressing circulating estrogen concentrations, with 38 ± 24% (mean ± sd; P = 0.002 vs. baseline) and 32 ± 29% (P = 0.008) decreases in estradiol concentrations, 71 ± 12% (P < 0.0001) and 74 ± 12% (P < 0.0001) decreases in estrone concentrations, and 45 ± 27% (P = 0.004) and 51 ± 20% (P = 0.02) decreases in estrone sulfate concentrations after doses of 25 and 50 mg, respectively. There was an increase in circulating testosterone concentrations after both 25 mg (60 ± 58%; P = 0.001) and 50 mg (56 ± 48%; P = 0.003) exemestane. Androstenedione concentrations were increased as well after 25 mg (32 ± 36%; P = 0.004) and 50 mg (47 ± 59%; P = 0.052) exemestane, respectively (Fig. 1 and Table 2). SHBG concentrations were decreased by 21 ± 7% (P = 0.0003) and 19 ± 39% (P = 0.18) at 25 and 50 mg exemestane, respectively. Free testosterone concentrations were increased by 117 ± 74% (P = 0.0001) and 154 ± 95% (P < 0.0001) at both doses, due to the decrease in SHBG and the increase in total testosterone. No effect on circulating dehydroepiandrosterone sulfate was observed at either dose. Serum cortisol concentrations increased significantly (38 ± 39%; P = 0.008) with the 25-mg dose, but not the 50-mg dose, yet the increase was well within the normal range of cortisol concentrations. Plasma IGF-I decreased significantly (−13 ± 11%; P = 0.008) after the 25-mg dose, but not the 50-mg dose. Similarly, IGF-binding protein-3 showed a trend toward lower concentrations after the 25-mg dose (−7 ± 13%; P = 0.09), but not the 50-mg dose. There were no changes in circulating serum triglycerides, cholesterol, or LDL or HDL cholesterol concentrations with either dose of exemestane. Table 2 summarizes the results of the hormonal and lipid data.
I was specifically referencing the 70-80% figure you had posted about. TOTAL Estrogen drops by around that much but estradiol is only suppressed by 38 +/- 24%

We want to reduce estradiol specifically. Aromasin is a weak inhibitor of E2 compared to adex and letro.