What is common tragedy everywhere according to the passage?

All mammals, except man and the monkey, swim naturally from birth. For man, like the monkey, it is not instinctive to float. Deaths by drowning are common everywhere. In the United States alone, about 7,000 children under four drown each year.
     Everything possible is done to prevent such tragedies. One solution is particularly effective teaching children to swim while they are still babies. Most large towns in Florida and California already run lessons for babies and infants. The idea has spread to Europe where, in several countries, special courses are now arranged for children from seven to twenty-four months.
     The first step is to eradicate the child’ s fear of the water. Next, he is taught to float. Once he can do this naturally and without fear, the teacher can move on the breathing, and arm and leg movements. Before long, the child grasps the technique and can propel himself through the water.