Initially, British and Australian coins circulated in New Zealand. The devaluation of the New Zealand pound relative to sterling in the 1930s led to the issue of distinct New Zealand coins in 1933, in denominations of 3d, 6d, 1s, 2s (the florin) and 2½s (the half-crown), minted in 50% silver until 1946 and in cupro-nickel from 1947.
In 1940, bronze ½d and 1d coins were introduced. All these denominations were the same size and weight as their equivalents in the Australian and UK coinage (although Australia never minted the half-crown).
The specifications for the coin were (in measurement units of the time):
Diameter of Coin: 1.215 inches
Standard Weight: 145.83333 grains
Remedy Allowance (margin of error in weight): Not exceeding weight of one piece in 40 pieces.
The composition of the metal was:
1940, 1945-1959: 95.5% copper, 3% tin and 1.5% zinc
1941-1945, 1960-1965: 97% copper, 0.5% tin and 2.5% zinc.
In regards to statistics, it has to be noted that the mintage figures provided by the Reserve Bank of New Zealand include, in some cases (like the 1953 mintages), the proof issue of the year while in most other cases they do not.
According to the Reserve Bank of New Zealand, the total mintage of the denomination during its existence was 138,099,000 (138 mln). Counting the (few) known proof mintages, the total mintage adds up to 138,124,015 (138 mln).