'Year of' in the Bible

And it came to pass in the month Nisan, in the twentieth year of Artaxerxes the king, that wine was before him: and I took up the wine, and gave it unto the king. Now I had never been sad before in his presence.

Moreover from the time that I was appointed to be their governor in the land of Judah, from the twentieth year even unto the two and thirtieth year of Artaxerxes the king, that is, twelve years, I and my brethren have not eaten the food allowance of the governor.

But in all this time I was not at Jerusalem: for in the two and thirtieth year of Artaxerxes king of Babylon came I unto the king, and after certain days obtained I leave of the king: