You can't only compare doormen to doormen, because the number of people and doors have increased too. You need to compare doormen to doors. All the apartment buildings I've known people live at on Manhattan have only had automatic doors. You need to show that automatic doors replaced unguarded doors.
1) What proportion of doors had doormen before compared to now?
2) What proportion of the population was employed as doormen then and now?
3) What proportion of the population benefited from doormen then and now?
1) What proportion of doors had doormen before compared to now?
2) What proportion of the population was employed as doormen then and now?
3) What proportion of the population benefited from doormen then and now?