SYDNEY, Australia: Australia’s government defended its ban on social media for children under 16 on August 1, even as new data showed how hard it is to enforce the rule. The response came a day after the country’s internet safety regulator reported that more than 80 percent of Australian teenagers were still using social media three months into the ban. Australia introduced the law in December because of concerns about how social media affects children’s mental and physical health. However, it has faced criticism from major social media companies, many of which are based in the United States. After the regulator released its findings, Assistant Minister Andrew Leigh said the ban had already changed how parents think and talk about social media.