causes of ozone layer depletion

i upload the recourse what I want to take from 

i want to write one page what are causes of ozone layer depetion

i want to use quotation from the recourse  i up loaded 

like this According to National Graphic " About 90 percent of CFCs currently in the atmosphere were emitted by industrialized countries in the Northern Hemisphere, including the United States and Europe'' this quotation i will use it