select

t.Request_at Day,

round(sum(case when t.Status = 'completed' then 0 else 1 end) / count(*), 2) Rate

from Trips t

inner join Users u

on t.Client_Id = u.Users_Id and u.Banned = 'No'

where t.Request_at between '2013-10-01' and '2013-10-03'

group by t.Request_at