Returns the age-interpolated median of the GCDG references (Weber
et al, 2019). The working range is 0-4 years. This function should
be called when the key = "gsed" or key = "gcdg".
Usage
count_mu_gcdg(t)
Arguments
t
Decimal age, numeric vector
Value
A vector of length length(t) with the median of the GCDG references.