So, presumably the numbers for 2019 will be published towards the end of this year. Mintage numbers for 2018 were released in October of 2019. This is because mintage numbers won't be definite for these coins until the Royal Mint announce them. Please note, 20 circulation 50ps are listed at the bottom of the table and their mintage numbers are given as UNKNOWN.
So, each year it has a new mintage number showing the amount of the coin that was struck that year. For example, as you can see, the Britannia design 50p was issued multiple times but each year the coin was struck with a new date.
For anyone new to coin collecting, the mintage number is the number of copies issued of a particular coin. We have arranged them in order of rarity using their mintage number. The list in the table below covers every design of the new coin that has been manufactured since the size change in 1997.