SQL Server 2019

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create table #GUIDS (UUID varchar(40));

declare @i int = 0

while (@i < 100000)
begin

  insert into #GUIDS
  select newid()

  set @i = @i + 1
end;

select substring(uuid, 1, 1) as first_letter, cast(count(*) as float) as counter
into #guids_stats
from #GUIDS 
group by substring(uuid, 1, 1)
order by 2 desc;

100016 rows affected

select top(20) * from #guids;

UUID

2BDB667A-EB3E-41CF-B3EF-09EAB2E2DB7D

DA4FB0DB-6E52-43F3-9C6E-A70434F40448

27D7B9B2-4BA5-47B2-AE61-84F6D3B721C0

293CB3C4-24CD-4697-8975-4DE2FC6FB0B3

E2159BEF-4871-4FD3-A180-0FD278A5E294

538B9FF1-B2E6-4F2E-88A5-BA1EDCA95422

585C11CD-88A2-4D3F-87DF-D739C2E59267

B14A7C20-426B-4CEF-9BDA-D02749398144

06479929-3868-4946-94FA-47E31EAD3957

FFF6576F-D89E-4F85-878E-8A0716A34E34

D7DD9FA5-19B8-42A2-8B53-A0A5DDF24DED

30D93B21-F897-4758-960E-BB61B016A93D

DA686964-0E24-4889-9889-7F1FC6ECEC65

BC45FB21-C87E-43B3-944F-A550AAC3F60E

3F3A3448-2223-4C09-AC53-82155C13078F

658C8867-C5FF-4354-B50F-A3232BF0461E

25679F9D-132B-4405-99BA-CE05B462E365

10B20362-8E6F-420D-9F77-1D7F4272CCF8

3F220E27-7393-47E3-B7FC-E922A2EC509B

C791FF85-C0EC-457A-BB74-93AB9B390ADD

select * from #guids_stats order by counter desc;

first_letter
counter

7
6422

C
6346

0
6334

8
6312

6
6307

1
6274

B
6240

2
6238

9
6226

F
6223

3
6213

E
6211

4
6195

5
6168

D
6149

A
6142

select min(counter)/max(counter) as ratio from #guids_stats;

ratio

0.956399875428215

first_letter	counter
7	6422
C	6346
0	6334
8	6312
6	6307
1	6274
B	6240
2	6238
9	6226
F	6223
3	6213
E	6211
4	6195
5	6168
D	6149
A	6142