Don't get one, they're too expensive relative to the amount of population you gain at this stage (Seeing as how you only have a 500 infra city). If you want to build civil improvements, wait until ~800 or so and get a police station, since crime cause a lot more damage than disease.
The banks and shopping malls show averages, which since the column is labled "Totals/Averages" is technically correct. Though they really should be separate columns instead of some weird mix.
Meanwhile...as hundreds of players suspiciously start skyrocketing in infra...
Yes, this is most likely a glitch, unless Sheepy intended to hide a gamebreaking Easter Egg.