Pennsylvania German developed in the eighteenth century as the result of the immigration of approximately 81,000 German-speakers from Central Europe, including Switzerland, to southeastern Pennsylvania. The vast majority (96 percent) of these immigrants were of the Lutheran or German Reformed faith; of the remaining 4 percent, roughly one-half were Mennonites and only a few hundred were Amish. Whatever varieties of German they spoke in Europe, the Amish assimilated to the language of the majority, Pennsylvania German, which resembles most closely the German dialects spoken in the southeastern Palatinate, near the city of Mannheim. The influence of English on Pennsylvania German is often overstated. Only 10 to 15 percent of Pennsylvania German vocabulary is English-derived; its core grammatical structures remain Palatine German.