[How to get Annual Growth rate in Crosstab?]

Hi I am new in this and  i would like to ask how to produce annual Growth rate using crosstab?

to make it simple ,in my database it contains the Year, Item,quantity like this:

YEAR	ITEM	QUANTITY
2014	Book	35
2014	Pencil	56
2015	Book	67
2015	Pencil	50

 

 

now in my report query i filtered it by "YEAR". By creating crosstab i produced something like this:

	$F{Year}	Total Quantity Measure
$F{Item}	$V{Quantity_measure}	$V{Quantity_measure}

 

which shows something like this

	2014	2015	Total
Book	35	67	102
Pencil	56	50	106

 

I want to calculate the annual growth rate but cant manipulate the datas by Year as it only produces the total of both years, is there any way i can use the formula for annual growth rate in crosstab?

Can anyone give me a sample template or any info on how to do it? Thank you very much. I want to produce a report output like this:

 

	2014	2015	Growth Rate
Book	35	67	91.42%
Pencil	56	50	-10.71%