web scraping Olympics

from bs4 import BeautifulSoup
import urllib2
web='http://www.sports-reference.com/olympics/summer/2012/'
req = urllib2.Request(web)
page = urllib2.urlopen(req)
soup = BeautifulSoup(page, "lxml")
table = soup.find("div", { "class" : "table_container" })
cells=[]
for row in table.findAll("tr"):
    result = row.findAll("td")
    if len(result) == 6:
        dic = {}
        dic["Rank"] = result[0].get_text()
        dic["Country"] = result[1].get_text()
        dic["Gold"] = result[2].get_text()
        dic["Silver"] = result[3].get_text()
        dic["Bronze"] = result[4].get_text()
        dic["Total"] = result[5].get_text()
        cells.append(dic)
import pandas as pd
import numpy as np
data=pd.DataFrame(cells)
data['year']=np.repeat(2012,data.shape[0])
data.to_csv(r'output.txt', header=True, index=None, sep=',', mode='a')
webs=['http://www.sports-reference.com/olympics/summer/2008/',\
     'http://www.sports-reference.com/olympics/summer/2004/',\
     'http://www.sports-reference.com/olympics/summer/2000/',\
     'http://www.sports-reference.com/olympics/summer/1996/',\
     'http://www.sports-reference.com/olympics/summer/1992/',\
     'http://www.sports-reference.com/olympics/summer/1988/',\
      'http://www.sports-reference.com/olympics/summer/1984/',\
      'http://www.sports-reference.com/olympics/summer/1980/',\
      'http://www.sports-reference.com/olympics/summer/1976/',\
      'http://www.sports-reference.com/olympics/summer/1972/',\
      'http://www.sports-reference.com/olympics/summer/1968/',\
      'http://www.sports-reference.com/olympics/summer/1964/',\
      'http://www.sports-reference.com/olympics/summer/1960/',\
      'http://www.sports-reference.com/olympics/summer/1956/',\
      'http://www.sports-reference.com/olympics/summer/1952/',\
      'http://www.sports-reference.com/olympics/summer/1948/',\
      'http://www.sports-reference.com/olympics/summer/1936/',\
      'http://www.sports-reference.com/olympics/summer/1932/',\
      'http://www.sports-reference.com/olympics/summer/1928/',\
      'http://www.sports-reference.com/olympics/summer/1924/',\
      'http://www.sports-reference.com/olympics/summer/1920/',\
      'http://www.sports-reference.com/olympics/summer/1912/',\
      'http://www.sports-reference.com/olympics/summer/1908/',\
      'http://www.sports-reference.com/olympics/summer/1906/',\
      'http://www.sports-reference.com/olympics/summer/1904/',\
      'http://www.sports-reference.com/olympics/summer/1900/',\
      'http://www.sports-reference.com/olympics/summer/1896/']
years=[2008, 2004, 2000, 1996, 1992, 1988, 1984, 1980, 1976, 1972, 1968, 1964, 1960, 1956, 1952,\
      1948, 1936, 1932, 1928, 1924, 1920, 1912, 1908, 1906, 1904, 1900, 1896]
for i in range(len(webs)):
    req = urllib2.Request(webs[i])
    page = urllib2.urlopen(req)
    soup = BeautifulSoup(page, "lxml")
    table = soup.find("div", { "class" : "table_container" })
    cells=[]
    for row in table.findAll("tr"):
        result = row.findAll("td")
        if len(result) == 6:
            dic = {}
            dic["Rank"] = result[0].get_text()
            dic["Country"] = result[1].get_text()
            dic["Gold"] = result[2].get_text()
            dic["Silver"] = result[3].get_text()
            dic["Bronze"] = result[4].get_text()
            dic["Total"] = result[5].get_text()
            cells.append(dic)
    data=pd.DataFrame(cells)
    data['year']=np.repeat(years[i],data.shape[0])
    data.to_csv(r'output.txt', header=None, index=None, sep=',', mode='a')