"since_year","till_year","Number","Graph"
"1300","1399","3",""
"1400","1499","10",""
"1500","1599","112","="
"1600","1699","113","="
"1700","1799","178","=="
"1800","1899","2442","========================"
"1900","1999","2744","==========================="
"2000","2099","177","=="