According to ranker.com, asthma is the 7th most common diagnosis, with COPD falling to #37. However, according to the Detroit Free Press, based on the amount of asthma and COPD medicine prescribed, asthma and COPD are the 4th most commonly diagnosed diseases.
The evidence seems to suggest that there are a lot of people being prescribed asthma and COPD medications -- i.e. albuterol -- who have not been diagnosed with either asthma or COPD.
Many respiratory therapists observed this as a common truth years ago, as it is quite obvious that many of the people prescribed aerosolized albuterol, Duoneb, and Pulmicort do not need these medicines.
However, there was a study done a while back that proved the placebo effect of albuterol, whereby 50% of patients who were given albuterol noted that they felt better after the treatment, and 50% of those given the placebo noted that they felt better after the treatment.