rate among Jews declined in the 1960s and 1970s. Intermarriage increased; the intermarriage rate of Jewish males was 41% and of Jewish women 28% in the period of 1945–1949. By the 1990s, the percentage of intermarriage increased to some 52% of all Jewish marriages. Among males, or so-called "father Jews", the intermarriage rate is as high as 80%. Some within the Jewish community have tried to counter this trend, creating possibilities for single Jews to meet other single Jews. The dating sites Jingles and Jentl en Jewell are for that purpose. According to research by the (), numerous Dutch Jews earned an academic education. There are proportionally more Jewish Dutch women in the labor force than non-Jewish Dutch women. 1980s and onwards Since the late 20th century, a number of mostly Israeli and Russian Jews have immigrated to the Netherlands, the latter after the Soviet Union eased emigration and after its dissolution. Approximately one in three Dutch Jews was born elsewhere. The number of Israeli Jews living in the Netherlands (concentrated in Amsterdam) runs in the thousands (estimates run from 5,000 to 7,000 Israeli expatriates in the Netherlands, although some claims go as high as 12,000). A relatively small number of these Israeli Jews is connected to one of the religious Jewish institutions in the Netherlands. In the 21st century, some 10,000 Dutch Jews have emigrated to Israel. As of 2006, approximately 41,000 to 45,000 people in the Netherlands either identify as Jewish, or are defined as Jewish by halakha (Rabbinic law), by which persons with Jewish mothers are defined as Jewish. About 70% of these (approximately 30,000) have a Jewish mother. Another 30% have a Jewish father (some 10,000–15,000 persons; their number was estimated at 12,470 in April 2006). Orthodox Jews do not accept them as Jews unless they undergo a religious conversion through an Orthodox Bet Din. Most Dutch Jews live in the major cities in the west of the Netherlands (Amsterdam, Rotterdam, The Hague, Utrecht); some 44% of all Dutch Jews live in Amsterdam, which is considered the centre of Jewish life in the country. In 2000, 20% of the Jewish-Dutch population was 65 years or older; birth rates among Jews were low. An exception is the growing Orthodox Jewish population, especially in Amsterdam. There are some 150 synagogues present in the Netherlands; 50 are still used for religious services. Large Jewish communities in the Netherlands are