Excel question, deciles of various number of rows different, thousands, question

bpdulog

Here is what I am trying to do. I have columns of data, each of varying numbers of rows, that I want to calculate decile averages for. One column could have three hundred rows, which would mean 10 deciles of 30 rows each. I could then manually create an average formula for each of the ten deciles.
The problem is I have thousands of such columns of data, with different numbers of rows. It will take way too long to manually average the deciles. If they were all 30 rows to a decile it would be no problem.
So, does anyone know of a simple solution where one formula will be able to grab the average of the first decile (and 2 - 10 in subsequent formulas), while automatically accounting for whether there are 30 or 50 or whatever rows in that decile. Then I could just copy that formula for the other columns.