stat.rb

#!/usr/bin/env ruby
# encoding: utf-8

FNAME = 'ff'
@lag_data = {}

File.open(FNAME).each do |line|
  line.gsub!("\n",'')
  time_area = line.split[2]
  t1,t2,t3,t4,t5 = time_area.split("/").map(&:to_i)
  @server_lag = t5 - t1
  @lag_data[@server_lag] = @lag_data[@server_lag].to_i + 1
end

 @lag_data.sort.reverse.each do |key, val|
   @key=key
   @lag_data[key] = @lag_data.select{|k| k < @key}.values.inject(:+).to_i + val
 end

 @lag_data.sort.each {|k,v| puts [k,v] * "\t"}