How to get the Top, Middle and Bottom value of Mid-80%?

[Anonymous]

I want to sort the value by customer class, and get the Top, Middle and Bottom value from Mid-80%.

data:

LOAD * INLINE [

SalesRep, CustomerClass, CallFrequency

'Rep1', 'Class1', 2.3

'Rep1', 'Class2', 3.1

'Rep1', 'Class3', 1.7

'Rep2', 'Class1', 2.1

'Rep2', 'Class2', 2.8

'Rep2', 'Class3', 1.5

'Rep3', 'Class2', 2.5

...

...

...

'Rep131', 'Class1', 2.2

'Rep131', 'Class2', 2.9

'Rep131', 'Class3', 2.0

'Rep132', 'Class3', 2.4

];

The following table is what I want, but I don't how to write the expression of TopOfMid80, BottomOfMid80 and MidOfMid80.

CustomerClass	NoOfSalesRep	MaxFrequenct	MinFrequency	TopOfMid80	BottomOfMid80	MidOfMid80
Class1	130	3.8	0.2
Class2	N
Class3	N

For example, in every class, I want to sort the Frequency as follow,

Class1

rankid	Frequency
1	0.2
2	0.4
3	0.5
…
…
…
127	3.1
128	3.2
129	3.5
130	3.8

Mid80 means the middle 80% of ranked list, and #14 - #117 rankid are in Mid80, #14 is BottomOfMid80, #117 is TopOfMid80, #65(or #66) is MidOfMid80.