使用PHP存储的CSV样式值对db行中的元素进行计数和分组

I've been stuck on this for a while and thought I would run it by the experts!

I have a db table row with values stored in this format (I know - not a good idea but it's what I got).

4,4,3,4,2
4,4,3,2,2
2,4,3,4,2
4,2,3,4,2

Basically, each row has 4 values separated by a comma. Each 'spot' can have values 1 to 5.

What I'm looking to do it be able to count how many times I have 1 in the first position, 2 in the first position...., 1 in the second position, 2 in the second position, etc...

I've been playing with loops and explode() but I'm not getting far!

Thanks!!