original passage: Cluster headaches are relatively uncommon. They affect only 1–3 per thousand people in the world. Cluster headaches affect approximately three times as many men as women.
original sentence: Cluster headaches are relatively uncommon.
sentence2: Knowing the relative probabilities shown above, whenever you see an expensively-produced TV commercial for chronic-migraine medication, would you be justified in thinking that too little time and money is being devoted to the arguably greater problem of cluster headaches?
sentence1: Cluster headaches are quite rare . They affect only 1–3 per thousand people in the world. Cluster headaches affect approximately three times as many men as women.