**Signatures for decades**

Why complicate life. An easy way to identify the decades is a 5-digit number where each digit represents the number of occurences in each decade (and 0 can be used).

So for draw #2020 with 14-18-22-23-31-45, it becomes 02211 and for draw # 1993 with 01-05-18-19-24-28, we get 22200.

Values can then go from 00005 to 50000. This allow for easy indexing, sorting, calculating frequencies, etc.

And I have to agree with you for the choice of decades. For me, decades are respectively 1-9, 10-19, 20-29, 30-39 and 40-49.