Modules & VBA :: Counting With SQL

I built a query "WplatyKlienci" which sum all of payments "Sumawplat" from my clients "klient".

Code:

SELECT SUM(tblWycenaZakonczone.cenanetto) AS Sumawplat, tblKlienci.nazwaSkrocona AS klient
FROM tblWycenaZakonczone INNER JOIN (tblZleceniaZakonczone INNER JOIN TblKlienci ON tblZleceniaZakonczone.id_k = tblKlienci.id_k) ON tblWycenaZakonczone.id_zlecenia = tblZleceniaZakonczone.id_zlecenia
WHERE tblWycenaZakonczone.cenanetto is not null
GROUP BY tblKlienci.nazwaskrocona;

Now I need to know 2 things and I have problem with counting in sql:/

1) what percentage of the total amount represents a particular client.
2) I want to create a graph, so I need to do another query, which shows values form no. 1 only for 10 clients with the largest payments + one position named "others" which represents rest of clients