"since_year","till_year","Number","Graph"
"1200","1299","1",""
"1400","1499","30",""
"1500","1599","86","="
"1600","1699","132","="
"1700","1799","499","====="
"1800","1899","1047","=========="
"1900","1999","1482","==============="
"2000","2099","225","=="