demdata: Demographic data

#' Permament and long-term arrivals to and departures from New Zealand,
#' 1997-2016.
#'
#' A permanent and long-term arrival is an international arrival of a
#' person who intends to reside in the country for at least on year.
#' A permanent and long-term departure is an international departure
#' of a person who intends to reside out of the country for at least
#' one year.
#'
#' The years are June years.  For instance, the year "1997" runs from 1 July 1996
#' to 30 Jun 1997.
#'
#' The data derive from international arrival and departure cards filled
#' out when entering and leaving the country.
#' 
#' @format An array with dimensions "age", "sex", "region", and "year"
#'
#' @source Custom tabulation from Statistics New Zealand.
#'
#' @seealso \code{\link{nz.popn.reg}}, \code{\link{nz.births.reg}},
#' \code{\link{nz.deaths.reg}}, \code{\link{nz.int.mig.reg}}.
"nz.ext.mig.reg"