>>> for p in g.get_citytotalpopulation_list():...     print "%s %s" % (p.date.year, p.get_next_by_date().date.year)... 1910 19101920 19201930 19301940 19401950 19501960 19601970 19701980 19801990 19902000 20002000 20002001 20012002 20022003 20032004 20042005 2005