Here are the rules about Tatkal issued in 2009. If there have been any changes please advise source:
Instead of full coach being presently nominated as Tatkal Coach, there will be Tatkal quota in each train in 2A, 3A, AC Chair Car, Sleeper and 2S (Second Sitting) classes as under:-
Classes No. of berths to be earmarked in trains with average occupancy level of Tatkal Quota
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Less than 80% More than 80%
2 AC 4 Berths Per Coach 10 Berths Per Coach
3 AC 6 Berths Per Coach 16 Berths Per Coach
AC Chair Car 6 Seats Per Coach 16 Seats Per Coach
SL 10% of the accommodation or one coach whichever is less 30% of the accommodation
Reserved Second Sitting (2S) 10% of the accommodation
In those trains and classes where average utilization of Tatkal accommodation during six months period i, e April to September is 80% and above, tatkal charges applicable during peak period will be charged through out the year i.e for both peak and non peak period.
There will be no separate Tatkal train defined. The unutilised Tatkal quota will get released to waitlisted passengers.

Apart from HO quotas there are other quotas such as PH (Parliament House) DF (Defence Personnel) LD (Ladies Quota) SRCTZN (senior citizen) which are minimal.
There is Pooled Quota, Remote Location quota, and RETURN JOURNEY QUOTA. EQ quota is separate and does NOT come under any category. But your statistical data does not seem correct.
PLEASE READ MY FIRST POSTING GIVEN AS...
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30 PER CENT OF SL CLASS BY READING THE SECOND POSTING..
Good wishes.

I did small analysis in the indianrailinfo site. Here is the details of the same
train number 6210
Source : Mysore
Destination: Ajmer
If I select the date say 3 months doen the line. The...
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site gives me the total availability
for 2 AC
General - 37
tatkal - 18
HQ - 4
All other quotas as 0
If there needs to 37 seats in general + 18 in tatkal then there will be minimum of 2 2AC coaches in the train.
hence total seating capacity - 2 * 46 = 92
general --> 37/92 - 40%
tatkal --> 18/92 - 20%
HQ --> 4/92 - 4%
Hence it adds upto 64%. So was just curious as to what happened to the rest 36%. Please let me know if I had missed some details in my calculation

Gr8 analysis!!!
But u have taken Mysore & Ajmer as ur station combo!!!!!!
There are in-between station.
1. Mysore to In-between station (RS Quota)
2. In-between to Ajmer station (RL Quota)
3....
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In-between Station pooled up (PQ Quota)
These must be utilizing remaining Berth!!!
Ur analysi has motivated me to find the answer!!!!!
I will be ready with answer in a short while, as to how much percentile, if its there!!!!