'Year' in the Bible

In the eighth month of the second year of Darius, the word of the Lord came to Zechariah the prophet, the son of Berechiah, the son of Iddo saying,

On the twenty-fourth day of the eleventh month, which is the month Shebat, in the second year of Darius, the word of the Lord came to Zechariah the prophet, the son of Berechiah, the son of Iddo, as follows:

In the fourth year of King Darius, the word of the Lord came to Zechariah on the fourth day of the ninth month, which is Chislev.

Then it will come about that any who are left of all the nations that went against Jerusalem will go up from year to year to worship the King, the Lord of hosts, and to celebrate the Feast of Booths.