Pivot Table - calculated field question

[SeanDamnit]

Hello,

I have data that looks like this:

Excel Workbook
	A	B	C	D	E	F
1	Invoiced By	Description	Tracking #	DistrictName	SALE/REFUND	SALE MONTH
2	Newbury Plaza-Service Center	SAMSUNG EPIC 4G	268435460202375837	Albany	1	Jun-11
3	Berkshire Mall-Service Center	HTC EVO 4G BLACK	270113179914734266	Albany	1	Jun-11
4	Crossgates Mall 2-Service Center	SAMSUNG RECLAIM M560 GREY	268435459500375412	Albany	0	Jun-11
5	Crossgates Mall 1-Service Center	HTC EVO SHIFT 4G	270113179913796650	Albany	1	Jun-11
6	Aviation Mall	LG OPTIMUS S (LS670) PURPLE	270113180104018434	Albany	1	Jun-11
7	Aviation Mall	SAMSUNG RECLAIM M560 GREY	268435459500318356	Albany	1	Jun-11
8	Crossgates Mall 1-Service Center	LG OPTIMUS S (LS670) GREY	270113180103950183	Albany	0	Jun-11
9	Crossgates Mall 2-Service Center	SAMSUNG EPIC 4G	268435460202420092	Albany	1	Jun-11
10	Berkshire Mall-Service Center	VIRGIN MOBILE KYOCERA LOFT Paylo	268435457814288275	Albany	1	Jun-11
11	Crossgates Mall 1-Service Center	BLACKBERRY STYLE ( 9670) PURPLE	268435459709931592	Albany	1	Jun-11
12	Rotterdam Square	LG OPTIMUS S (LS670) GREY	270113180103903301	Albany	1	Jun-11
13	Crossgates Mall 2-Service Center	SAMSUNG EPIC 4G	268435460202419988	Albany	0	Jun-11
14	Eastfield Mall 1	NEXUS S 4G GOOGLE	268435460202709228	CT	1	Jun-11
15	Brass Mill Center 1	LG RUMOR TOUCH (LN510) BLUE	268435460015415772	CT	0	Jun-11
16	Eastfield Mall 1	BLACKBERRY STYLE ( 9670) GREY	268435459710081551	CT	0	Jun-11
17	Trumbull Mall	LG OPTIMUS S (LS670) GREY	270113180103938281	CT	1	Jun-11
18	Eastfield Mall 1	LG OPTIMUS S (LS670) GREY	270113180103904257	CT	1	Jun-11
19	Brass Mill Center 1	LG OPTIMUS S (LS670) GREY	270113180103948756	CT	1	Jun-11
20	Brass Mill Center 1	LG OPTIMUS S (LS670) PURPLE	21202216161721252323221923	CT	1	Jun-11
21	Eastfield Mall 1	HTC EVO 4G BLACK	270113179914745799	CT	0	Jun-11
22	Eastfield Mall 1	BLACKBERRY STYLE ( 9670) PURPLE	268435459709931358	CT	1	Jun-11
23	Eastfield Mall 1	NEXUS S 4G GOOGLE	268435460202666733	CT	1	Jun-11
24	Montgomery Mall	BLACKBERRY STYLE ( 9670) GREY	268435459710146203	DC	1	Aug-11
25	PG Plaza	BLACKBERRY STYLE ( 9670) GREY	268435459710146046	DC	0	Aug-11
26	PG Plaza	SAMSUNG M360	268435460112027388	DC	1	Aug-11
27	Montgomery Mall	LG OPTIMUS S (LS670) GREY	270113180103948937	DC	1	Aug-11
Sheet3

This is a sales report. The SALE/REFUND column will show 1 if this serial# was sold and has yet to be returned, and 0 shows that it was returned.

I'm trying to create an analysis to see a return ratio by Description, Store (invoiced by), District, and Sale Month. I use a pivot table and it looks like this:

(note that I renamed the "0" and "1" columns to "Refund" and "Sale"

Now to my actual question: I want to add another column to the right for RETURN RATIO, which should simply be REFUND divided by SALE, or SUM of SALE/REFUND column divided by COUNT of SALE/REFUND column. My assumption is that a calculated field would do this for me, but since the data is coming from the same field, I don't know how to actually do this...

I'm thinking that I'm just missing something simple here. Pivot tables are still relatively new to me.

Any help you can provide is much appreciated