Hoe can I show a percentage increase by month?

[#1]

Month     Value    

11/2014 - 34000    

10/2014 - 30000

09/2014 - 25000

How can I obtain values that show % increase like,

(September's value will be subtracted from October's) / September's value?

Month        % Increase

11/2014 -     0.13333

10/2014 -     0.20

09/2014 -

[#2]

(sales-above(sales))/above(sales)

Add this expression and format it to percentage

[#3]

Please find the attachment as well.