You might want to make yourself familiar with the window functions Window Functions - SAP HANA SQL and System Views Reference - SAP Library of SAP HANA.
As I am not sure about your use case, here's an example I fiddled together years ago. It's to find out what threshold to pick for long running statements trace. There you want to focus on the top 5 percent (or so) of statements that run slow.
What time to pick for expensive statements trace?
select n_tile*25 || '% of all statements' as statment_group, max(avg_execution_time) as upper_runtime_boundary from ( select avg_execution_time, ntile (4) over (order by avg_execution_time) n_tile from "PUBLIC"."M_SQL_PLAN_CACHE") group by n_tile order by n_tile;
STATMENT_GROUP UPPER_RUNTIME_BOUNDARY 25% of all statements 0 50% of all statements 943 75% of all statements 14.369 100% of all statements 21.395.089
So the ntile buckets the data into n buckets. From here it shouldn't be difficult to get to what you asked for.
Other than that, I strongly recommend to actually do the search-first-then-post exercise as this is a pretty standard question for SQL programming.
Cheers,
Lars