Create Sample table based on users Productivity

Hi Expert 

i had question that i want to get random table before, but the answer doesn,t work in my project

what i want to ask is 
from source data like this : 

 hope can generate the Productivity by "username Ori" which mean = count by username

and from that productivity i want to get the 3% (productivity * 0.03) like this : 

and then I want to have Random sample table based on 3% measurement from

productivity each user like below. 

please help, the data is attached

>>> DataSource <<<