The sun emits two types of ultraviolet radiation that damage skin: UV-A, which causes premature wrinkles, and UV-B, which causes sunburn. Until about ten years ago, sunscreens protected against UV-B radiation but not against UV-A radiation.
The statement 'People who wear sunscreen now are less likely to become sunburned than were people who spent the same amount of time in the sun wearing sunscreen ten years ago' is best supported by the information above.