CREATE TABLE table_13559 ("Year" CLOB, "1851" CLOB, "1861" CLOB, "1871" CLOB, "1881" CLOB)

What's the 1851 when 1881 had 764?
SELECT "1851" FROM table_13559 WHERE "1881" = '764'
SELECT "1851" FROM "table_13559" WHERE "1881" = '764'