puts "autonomous_system_name\tcider\tpercentage"
@all_stats.each do |stat|
  asys = stat.autonomous_system
  name = asys.name
  pgbb = stat.percentages_grouped_by_block
  pgbb.each do |k ,v|
    puts "#{name}\t#{k}\t#{v}"
  end
end

__END__
input
@all_stats=
[#<LowIpAlertStat:0x7f5af0527cc0
  @autonomous_system=
   #<AutonomousSystem id: 11, name: "DFW", number: 33070, description: "DFW", created_at: nil, updated_at: "2013-09-04 19:30:06", owner_number: "DCO1", private: false, autonomous_system_id: nil, network_environment_id: 55, low_ip_alert_check: true, low_ip_alert_threshold: 70>,
 @percentages_grouped_by_block=
   {"166.78.42.0/23"=>100.0,
    "166.78.33.0/24"=>100.0,
    "209.61.129.0/24"=>100.0,
    "166.78.36.0/22"=>99.21875,
    "166.78.32.0/24"=>100.0,
    "209.61.131.0/24"=>100.0,
    "209.61.128.0/24"=>100.0,
    "50.56.228.0/24"=>100.0},>]
=>nil

desired out put
autonomous_system_name   cider                    percentage
DFW                      166.78.42.0/23            100
DFW                      166.78.33.0/24            100
DFW                      209.61.129.0/24           100.0
DFW                      166.78.36.0/22            99.21875