Calling in sick to work

As least as possible. I have never been out sick more than 3x in a year.

Reasonable or truthful? Teachers are given 10 sick days per year, averaging one sick day per every 20 days of work. That should probably set a good example if you need one. But I believe to call in sick will inconvenience someone, cost someone, and will reflect upon work record and recommendations. It is probably something to try to avoid if possible, unless very sick.

No more than 5x in one year.

Its best to not call out but when you have to you have to, 3 times a year.

twice a year.

To me reasonable means calling in sick when you're actually sick, or maybe if you're just not really into it and won't be productive (rarely). If you use sick days when you're not really sick, and you're allowed only a limited number of sick days, you'll come up short if you actually get sick (like the flu) and really need to take those sick days.