PERCENTRANK(array,x,significance)
array: range of numeric values
x: data point to be ranked
significance: number of significant digits, defaults to 3
If array contains no data points, this function returns a #NUM! error. If significance is less than one, this function returns a #NUM! error. If x exceeds the largest value or is less than the smallest value in array, this function returns a #NUM! error. If x does not match any of the values in array or x matches more than once, this function interpolates the returned value.