Help with formula to calculate average percentage for each consecutive cell based on the number of cells

[Sparker65]

Hi, this is my first time post and I need help with a formula to calculate the average percentage for each cell including the previous cell. For example, cell I2(Apr-18) contains a percentage, I would like to add that percentage to cell J2(May-18) and find the average, and for cell K2(Jun-18), I would like to add cells I2, J2, and K2 and find the average. The desired results are in columns 1-3. I have 12 cells in each row. I can do it manually but I would like a formula. See sample data below.

Thanks!

Apr-18	May-18	Jun-18	Jul-18	Aug-18	Sep-18	Oct-18	Nov-18	Dec-18	Jan-19	Feb-19	Mar-19	Column1	Column2	Column3
95.65%	97.83%	97.83%	97.83%	89.13%	91.30%	89.13%	86.96%	93.48%	97.8%	93.5%	91.3%	95.65%	96.74%	97.10%

<colgroup><col><col><col><col><col><col><col><col><col><col><col span="2"><col span="3"></colgroup><tbody>
</tbody>

 

[JoeMo]

If the 1st percentage is in I2 then in cell U2: =AVERAGE($I2:I2)
and copy to the right.

 

[Sparker65]

Hi Joe,

Thanks so much! I forgot the $ in the formula. I really appreciate the assistance.