Richness headcount ratio is a proportion of the population with incomes above the affluence line. Weighted version (with weights \(w_1,w_2,...,w_n\))
of this ratio is given by:
$$R^{HC}(\boldsymbol{x},\boldsymbol{w},\rho_w) = \frac{\sum_{i=1}^n \boldsymbol{1}_{x_i > \rho_w}w_i}{\sum_{i=1}^n{w_i}},$$
where \(x_i\) is an income of individual \(i\), \(n\) is the number of individuals, \(\rho_w\) is the richness line,\(\boldsymbol{1}_{(\cdot)}\)
denotes the indicator function, which is equal to 1 when its argument is true and 0 otherwise.