Select the ranodm percent of the line in the data set

Hello ;
I have a file which has one column with 7200 ID. These line have been repeated for certain of these ID. for example, ID number 200 repeated 3 times, ID number 201 repeated 2 times and etc. How could I select 20% of the ID numbers randomly without repetition?

Regards
Sajjad

I believe this info will do it for you, check it out: