(S (S (S (NP (BASENP (RB Nearly) (NNS three-fourths)) (PP (IN of) (BASENP (NNS boys)))) (VP (VBD reported) (S (VP (VBG having) (VP (VBN masturbated)))))) (COMMA ,) (S (VP (VBN compared) (PP (TO to) (NP (NP (ADVP (RB only)) (BASENP (QP (ADVP (RBR less) (IN than)) (NN half)))) (PP (IN of) (BASENP (NNS girls)))))))) (PERIOD .))