say I have a postgresql table with the following values:

id | value
----------
1  | 4
2  | 8
3  | 100
4  | 5
5  | 7

If I use postgresql to calculate the average, it gives me an average of 24.8 because the high value of 100 has great impact on the calculation. While in fact I would like to find an average somewhere around 6 and eliminate the extreme(s).

I am looking for a way to eliminate extremes and want to do this "statistically correct". The extreme's cannot be fixed. I cannot say; If a value is over X, it has to be eliminated.

I have been bending my head on the postgresql aggregate functions but cannot put my finger on what is right for me to use. Any suggestions?