I just had a colonoscopy and I believed they hooked me to an IV and injected a sedative of some sort, but it wasn't really effective as even though I was drowsy, I never went to sleep, and was fully conscious and aware (mentally and physically) of the colonoscopy. Is it normal for patients to be awake during their colonoscopy or are we to be completely knocked out?
No, you are not supposed to get full anesthesia for a colonoscopy. Anesthesia is too dangerous and only used in really invasive procedures.
Colonoscopies are sometimes done without any medication (the physiologically safest way) and sometimes with sedation. Sedation means that you get something to keep you calm, not that you are put to sleep. That's what you had in your procedure.
See for example http://lup.lub.lu.se/search/record/1136597 for numbers. Nowhere is anesthesia even mentioned.
Surely it depends on local guidelines, you could be given propofol or benzodiazepines but it can be done on hypnosis or acupuncture or on nothing. You could get a PTSD afterwards. It is a serious procedure and has a perforation risks and is not wide-spread today thanks to modern ultrasound, CT and MRI and PET.