gistfile1.rb

year = 2013
months = (1..6)

months.each do |month|
  start_date = Date.new(year,month,1)
  end_date = start_date + 1.month
  total = Payment.where(item: 'subscription', transaction_state: 'success', created_at: start_date..end_date).sum(:amount_in_cents)/100.0
  puts "year: #{year} month: #{month} total_subs: #{total}"
end