Plotting histogram with line graph

histline.do

webuse nlswork, clear

gen count_ln_wage = !missing(ln_wage)
collapse (sum) count_ln_wage (mean) ln_wage, by(grade year)

label var count_ln_wage "Number of individuals"
label var ln_wage       "Average log(wage)"

levelsof year, local(years)
foreach yr of local years {
  graph twoway (bar count_ln_wage grade, yaxis(2)) (line ln_wage grade, yaxis(1) connect(stairstep)) if year == `yr', title("`yr'")
}