code: public double getPercentileAtOrBelowValue(final long value) {
          if (getTotalCount() == 0) {
              return 100.0;
          }
          final int targetIndex = Math.min(countsArrayIndex(value), (countsArrayLength - 1));
          long totalToCurrentIndex = 0;
          for (int i = 0; i <= targetIndex; i++) {
              totalToCurrentIndex += getCountAtIndex(i);
          }
          return (100.0 * totalToCurrentIndex) / getTotalCount();
      }
docs: Get the percentile at a given value.
  The percentile returned is the percentile of values recorded in the histogram that are smaller
  than or equivalent to the given value.
  <p>
  Note that two values are "equivalent" in this statement if
  {@link org.HdrHistogram_voltpatches.AbstractHistogram#valuesAreEquivalent} would return true.
  
  @param value The value for which to return the associated percentile
  @return The percentile of values recorded in the histogram that are smaller than or equivalent
  to the given value.