Need query to get data as per below

Input Table is

required output is

as first record is 15000, so its rank is 1
as second record is 15000, so its rank is also 1
as third record is 14500, so its rank is also 3 and not 2 because even though first two records have same record, the count is now 2 so new rank will be 3 for third record

need query for the same..

here is script for data preparation

SELECT 15000 TARGET,
       '' AS AGENT,
       NULL RANKA
INTO #TABLEA;  

INSERT INTO #TABLEA
VALUES (1400, 'B', NULL);

>Solution :

You can do it using rank() to get the rank, and rank/count to get Percentile

with cte as (
  select Target, Agent, rank() over (partition by Agent order by Target desc) as Ranka
  from TableA
)
select Target, Agent, cast(Ranka as float)/CAST(count(*) over (partition by Agent) AS FLOAT)*100 as Percentile
from cte

Or this if you dont need Percentile :

select Target, Agent, rank() over (partition by Agent order by Target desc) as Ranka
from TableA

Demo here