How to graph average growth?

[ExcelLLAA]

I have a graph with two lines (2012 and 2013 data). I want to calculate the average growth rate (they only go up over time) between the two and the average growth rate from one week to the next for 2013 only. The x axis is dates (e.g. July1-8) and the y-axis is money. When I tried other formulas it said I was trying to divide by 0. Is this becuase the x-axis is not represented in actual numbers? I also want to do this in another graph where the x-axis only has weeks (e.g. "week 1", "week 2", etc.) Thanks for your help in advance!

 

[Andrew Poulsom]

July1-8 is text not a date. What formula did you try?

 

[ExcelLLAA]

I tried to do a forecast formula because I want to know avg growth and projected avg growth. I tried =FORECAST(X, known ys, known xs). Sorry I'm tech challenged.

 

[Andrew Poulsom]

If your data is linear you can use the ROW function for x and known x's:

Excel 2010
	A	B
1	Week	Data
2	Week 1	5
3	Week 2	10
4	Week 3	15
5	Week 4	20
6	Week 5	25
7	Week 6	30
8	Week 7	35
9	Week 8	40
10	Week 9	45
11	Week 10	50
12	Week 11	55
Sheet21

Cell Formulas
Range	Formula
B12	=FORECAST(ROW(A12),B2:B11,ROW(A2:A11))

 

[ExcelLLAA]

That works. Thanks!