Complex correlations

[Razyg]

Hi all
I've been trying to find a way to compare and code correlations,
the following is a list of mean values:
Day Mean
1 58
2 12
3 35
4 14
5 42
6 9
7 12
LSD= 17
Any difference between means smaller than the 'least significant difference' (LSD) is not significant, anything equal to or over LSD is significant.
I need to attribute means to groups; the means within a group are not significantly different from each other but are significantly different from the means in other groups.
Groups would be letters a - g
Values can be in more than one group
The group with the smallest mean must be group 'a', the next mean value significantly different from any member of group 'a' must begin group 'b' and so on.
The above example should read:
Day Mean Group
1 58 c
2 12 a
3 35 b
4 14 a
5 42 b,c
6 9 a
7 12 a

Hopefully you can help before I pull all my hair out!