In reply to Ksharp.

Thanks for writing. The CL=EXACT method produces the Clopper-Pearson CI, which uses probabilities from the discrete binomial distribution. The doc for PROC FREQ states:
"The confidence coefficient (coverage probability) of the exact (Clopper-Pearson) interval is not exactly (1 - α) but is at least (1 - α). Thus, this confidence interval is conservative. Unless the sample size is large, the actual coverage probability can be much larger than the target value."