Is it normal to get erectile dysfunction?

Yes. Erectile dysfunction is a normal process of aging. The incidence begins to rise when a man enter his 30's and 40's. The degree of severity that a patient experiencses is variable. The severity depends on the overall health of the patient, medications taken, exercising, other other comorbidites such as diabetes and hypertension.
Not really. "dysfunction" implies a disease. An inability to "get it up" at your age (22) most likely is not due to erectile dysfunction but anxiety or drugs (alcohol). As we age, erectile strength tends to not be as great, and it can take longer to get erect, but this often is not "dysfunction" but rather normal aging. Erectile dysfunction, however, is common due to comorbidities (esp heart disease) and meds.
What is normal? It's normal to get fat as we age if we don't take care of ourselves but that doesn't make obesity "normal". So while ed is common, i don't think it's "normal". But given the statistics of smoking, excess alcohol consumption, obesity, diabetes, high cholesterol/blood pressure & depression, as well as many drug side effects, it's not surprising that common is mistaken for "normal".