We see in the All-Countries dataset that the percent of the population that is elderly (over 65 years old) is 17.0 in Austria and 15.9 in Denmark. Suppose we take random samples of size 200 from each of these countries and compute the difference in sample proportions p̂_A − p̂_D, where p̂_A represents the proportion of the sample that is elderly in Austria and p̂_D represents the proportion of the sample that is elderly in Denmark. Find the mean and standard deviation of the differences in sample proportions.