NEW DELHI: One in four of those reporting non-marital sexual violence are adolescents in the 15-19 age group, pointing to higher vulnerability of minors who are also less likely to report such instances to police as compared to adult women, a study on the lack of disclosure of such crimes has found.Overall, two in five female survivors do not inform anyone of sexual violence suffered. The findings on the lack of disclosure are part of an analysis of the national family health survey - 4 (2015-16) that show of 4.4 lakh adolescent girls who were victims of sexual violence in the year preceding the survey, 35% neither sought help or told anyone. Only 0.1% girls reported the violence to police. The data analysis for the 15-49 year age group shows that 14 lakh women experienced sexual violence from someone outside their marriage. Here too, 42% neither sought help nor told anyone. Only 1.9% reported the violence to police.The analysis on non-marital sexual violence in India is led by Dr Anita Raj , director of the Centre for Gender Equity and Health, University of California , in collaboration with the Mumbai-based International Institute for Population Sciences.The study concludes non-marital sexual violence is a "pervasive concern" affecting far greater number of women and adolescent girls than reported cases suggest. "More than 2 in 5 never tell anyone of this abuse. Adolescent girls 15-19 years are disproportionately affected and even less likely to report the crime to police. Most assailants of this violence are known to their victims, as partners, family members or friends. Stranger-perpetrated sexual violence against women and adolescents is less common," the analysis found. The study suggest only 5% adolescents reported the perpetrator to be a stranger. The study suggests that since in most cases the perpetrator is a known person, prevention strategies need to focus on "potential perpetrators". It is emphasised that mobility restrictions on girls out of fear of strangers will not work as a preventive measure.The study recommends reduction in stigmatisation and improved police response can facilitate victims' disclosure. "This prevalence was calculated for the population of all women aged 15-49 years, and by age category," Dr Raj said.