Excel 2007 : Counting multiple periods - presenting results at the end of each one

Hi everyone,

We have a column with multiple groups of numbers which are representing periods.
Between these periods we have blank cells. Every group has its own number.
We need a formula to count the numbers which appear in one column and show the results at the next one, presenting at the end of each period the results of the counting.

In the attached file you'll find a small but clear example.

Any help would be greatly appreciated !!!