List numbers by order of frequency?

I have an section of numbers (5x5) that has several repeating numbers. I have another section of the same size in which I'd like to store those same numbers, in order of frequency (most frequent first).

Source:

4 6 9 3 2
7 3 2 5 6
0 1 9 8 4
4 7 1 5 9
2 5 4 8 6

Target:

4 6 9 2 5
3 7 1 8 0
- - - - -
- - - - -
- - - - -

The numbers would be of an arbitrary range, not just 0-9. The order of same-frequency numbers can be by either value or order of appearance. The target section must be filled row by row, from left to right.

Anybody know how I might accomplish this?

So here's as close as I was able to get so far... Maybe it's close enough for you? Or maybe it puts you on the right path to solving it completely... Or maybe someone comes along and has something so much more simple. In any case, attached is my effort. I hope it is helpful to you.