With your data starting in A1
In C1: + B1
In C2: =IF(B2,AVERAGE($B$1:B2),C1) 'note the absolute reference on B1
This is copied down the column
You might be more comfortable with =IF(B20, bit Excel will take any numeric
value as meaning TRUE in a formula such as =IF(B2, .....
best wishes
Bernard

"John Smith" wrote in message
...

"Bernard Liengme" wrote in message
...
How about a mini example data set?
Bernard


28Jan2010---21---21
29Jan2010---37---29
30Jan2010---23---27
31Jan2010---39---30 (today)
01Feb2010----0---30
02Feb2010----0---30
02Feb2010----0---30