PERCENTRANK function
Returns the rank of a value in a data set as a percentage of the data set. This function can be used to evaluate the relative standing of a value within a data set. For example, you can use PERCENTRANK to evaluate the standing of an aptitude test score among all scores for the test.
For more information about the new functions, see PERCENTRANK.EXC function and PERCENTRANK.INC function.
Syntax
PERCENTRANK(array,x,[significance])
The PERCENTRANK function syntax has the following arguments:

Array Required. The array or range of data with numeric values that defines relative standing.

X Required. The value for which you want to know the rank.

Significance Optional. A value that identifies the number of significant digits for the returned percentage value. If omitted, PERCENTRANK uses three digits (0.xxx).
Remarks

If array is empty, PERCENTRANK returns the #NUM! error value.

If significance < 1, PERCENTRANK returns the #NUM! error value.

If x does not match one of the values in array, PERCENTRANK interpolates to return the correct percentage rank.
Example
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
Data 

13 

12 

11 

8 

4 

3 

2 

1 

1 

1 

Formula 
Description (Result) 
Result 
=PERCENTRANK(A2:A11,2) 
Percent rank of 2 in the range A2:A11. Result is 0.333 because three values in the set are less than 2, and six are greater than 2. Because 2 is found in the range (cell A8), the number of values less than 2 is divided by the sum of the number of values less than 2 and the number of values greater than 2. That is, 3/(3+6)=0.333. 
0.333 
=PERCENTRANK(A2:A11,4) 
Percent rank of 4 in the range A2:A11. Five values are less than 4, and four are greater. Following the example above, 5/(4+5)=0.555. 
0.555 
=PERCENTRANK(A2:A11,8) 
Percent rank of 8 in the range A2:A11. Six values are less than 8, and 3 are greater. Following the example above, 6/(6+3) =0.666. 
0.666 
=PERCENTRANK(A2:A11,5) 
Percent rank of 5 in the range A2:A11. Unlike the examples above, 5 is not found in the range. The PERCENTRANK of 5 is calculated by finding the onequarter mark between the PERCENTRANK of 4 and the PERCENTRANK of 8. This is (0.555)+(0.25*(0.6660.555)), or 0.583. 
0.583 