Calculating average for one column based on value existing in another column

Hi,

I have the following problem: I would like to calculate average productivity of two people who do not always work together.
I want to see if they are more productive individually than in a tandem and here's how the part of raw data looks like:

Date------- Employee1-------Employee2
31/10/2012------- 0.064------- 0.269
02/11/2012------- -0.177------- #N/A
03/11/2012------- -0.383------- #N/A
05/11/2012------- 0.005------- 1.100
07/11/2012------- 0.281------- 0.808
08/11/2012------- #N/A------- 0.840
11/11/2012------- #N/A------- 0.687
14/11/2012------- -0.225------- 0.986
17/11/2012------- 0.681------- -0.258


If there is an #N/A it means employee was not working that day.
So what I actually need is to have:
1. Average for both employees when they are working together
2. Avg for both employees when the other one was absent.

Any ideas will be really appreciated.
Thanks,

Leszczur

Woking in my head this should do it. Might need a tweak in the sheet though as I might have messed something up!

Employee 1 alone:

Formula:

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Employee 2 alone:

Formula:

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Employee 1 together:

Formula:

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Employee 2 together:

Formula:

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Perhaps I should have made myself clearer.
For calculating average for Employee 1 - I'm not only looking to ignore cells with "#N/A" value, but I want only those where in corresponding column for Employee 2 we have "#N/A".
So for the raw data of Employee 1 I want an average from row 2 and 3 (as Employee 2 was not at work). And for Employee 2 I want average of rows 6 and 7 (when Empl 1 was absent).

D'oh - yeah I knew something wasn't right, I gave you the inverse for the "alone" working. The ones for them both working together should still be correct.

Employee 1 alone:

Formula:

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Employee 2 alone:

Formula:

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Again, let me know if I'm just having one massive Monday brain fart!

WORKS! Many thanks mate!