What is the typical day care illness in the first year. My son has been sick since day care 10 mo-18 mo. Typical or poor hygiene?

Fairly typical. Kids in day care can have a new cold every month. Ultimately this is a good thing (so long as they're otherwise healthy) as the broad exposure to different viruses and "germs" helps their immune system to develop as it should - robust and able to handle lots of stuff later on. Kids who are raised in "sterile" surroundings often end up having problems like asthma and lots of allergies.
Many! When babies first start day care after being at home all their life, they are exposed to viruses and bacteria their bodies have never encountered, their immune systems have to build up their defenses and in the first months they seem to catch everything that is going around in the center. It subsides in a couple of months. If kids change rooms it starts over sometimes. For sure check cleanliness.
Typical. Day care syndrome. The more exposures at a young age the more likely you are to get many infections. Most babies will have 6-12 infections per year. Most will be minor and most are during the winter months.
Very common. It is very common for small children to get several "colds" (upper respiratory tract infections) once they are started at daycare.