Averages and sequences

Hi All,

Hoping someone out there can help.


I have the follow table of monthly Revenues for close to a 3 year period. I am trying to analyse monthly revenue increases. ie Sept 2012 minus Sept 2011 (this is the easy part)

Number of issues:
(a) if the series starts with a zero sequence the cells should not be included in the monthly comparison until there is an actual value. If the sequence is zero then output the comparison value as -0.01 so one can differentiate the cell and know not to include it in any calculation.

(b) the end sequence of some rows already contain -0.01, when comparing monthly figures these cells should be excluded from the analysis. ie cell AM3 should output as -0.01 along with cell AK7 - AM7 = -0.01

(c) output the average (in column AN) but exclude cells outputed from (a) (ie for row 5 do not include month 1 to 6) and any cell which is -0.01


If you need clarification let me know.


Thanks
hog