需要检索推荐消费最多的前5个推荐人

I need to get the TOP 5 referrers whos referrals spend the most money. I need to get:

1) the number of total referrals

2) the number of paying referrals only

3) the total amount those paying referrals have spent

So far this query returns the total paying referrals, but I need total referrals as well. Can it be done in 1 query or we need 2? Please help! Thank you!

SELECT t1.referrer as referrer, 
       count(t1.username) as total_referrals, 
       count(t2.username) as paying_referrals, 
       SUM(t2.payment) as total_payments
  FROM USER_DATA t1, PAYMENT_INFO t2 
 WHERE t1.username = t2.username  
 GROUP BY referrer
 ORDER BY total_payments DESC 
 LIMIT 0,5

USER_DATA (user data, about ~1000 records)

username   referrer    email   password ...
user1       user67
user2       user89
user3       user89  
user4       user57
user5       user57
user6       user89
user7       user67
user8       user89
...

PAYMENT_INFO (user payments, about ~300 records)

username    payment
user1        100
user1        200
user2        350
user1         50
user5        500
user1        200
user3        150
user2         80
...