Add 95% Confidence Intervals for Percentile Estimates

[kevintcaron]

Percentile Estimates need 95% Confidence intervals in order to match the National Exposure Report which can be done according to the Procedure to Estimate Percentiles found on the NER site.
The sample code requires SAS and SAS-callable SUDAAN. According to the reference, "Clopper-Pearson 95% confidence intervals around the estimated proportion are obtained using the method described by Korn and Graubard (1998)."