In 1982 Diana E. H. Russell, a feminist writer and activist, conducted the seminal study on marital rape. Her study surveyed a total of 930 women from San Francisco, California (50% non-response rate, non-English speaking Asian women were specifically excluded as non-reliable respondents), of whom 644 were married, divorced, or who self-identified as having a husband although not married. Six of these women (1%) self-assessed that they had been raped by their husbands, ex-husband, or de facto husbands. The survey interviewers, however, classified 74 (12%) of these women as having been raped. Of the 286 non-married women in the sample, 228 (80%) were classified by the survey interviewers as having been raped. Russell found that when repeated instances of rape as classified by the survey interviewers, by husbands or ex-husbands, over the entire course of the marriage are included, these account for 38% of all rape instances, in comparison to the remaining 62% occurring in non-marital instances.