As Trew mentioned, whith the stupid remint policy I wouldn't pay any premium for the Ox compared to other years, there has been a remint earlier this year though the mint didn't provide any office numbers, at least not that I'm aware of
Coins like Rabbits and Tigers were available at dealers for decent premiums till around June when spot dropped, now older years are not easy to find.
So till 2019, PM will still mint early years kilo lunars on a mint to order basis, below are the sales to date, however if the mint get big order for let's say the Mice or the Oxen, they will use they remint policy to supply the distributors
Mouse : 8,652
Ox : 15,923
Tiger : 33,774
Rabbit : 46,085
Dragon : 55,526
Snake : 11,970