Nicole Malliotakis, the Republican candidate for New York City mayor, says the number of sex crimes on the city’s subway system has increased since Mayor Bill de Blasio took office in 2014. "People are packed in like sardines," Malliotakis said in a new television ad, "and subway sex crimes are up over 50 percent." Sex crimes refer to acts of a sexual nature on the subway, like touching someone without consent or public lewdness. Riding the subway has been less than pleasant lately, with frequent delays and occasional equipment failures. But is Malliotakis right when she says riding the subway has become more dangerous as well?