<Tr> <Td> Marlin E. Olmsted </Td> <Td> Republican </Td> <Td> March 4, 1903--March 3, 1913 </Td> <Td> Redistricted from the 14th district and re-elected in 1902 . Re-elected in 1904 . Re-elected in 1906 . Re-elected in 1908 . Re-elected in 1910 . Retired . </Td> <Td> (Data unknown / missing .) </Td> </Tr> <Tr> <Td> Aaron S. Kreider </Td> <Td> Republican </Td> <Td> March 4, 1913--March 3, 1923 </Td> <Td> First elected in 1912 . Re-elected in 1914 . Re-elected in 1916 . Re-elected in 1918 . Re-elected in 1920 . Lost re-election . </Td> <Td> (Data unknown / missing .) </Td> </Tr> <Tr> <Td> Edward M. Beers </Td> <Td> Republican </Td> <Td> March 4, 1923--April 21, 1932 </Td> <Td> First elected in 1922 . Re-elected in 1924 . Re-elected in 1926 . Re-elected in 1928 . Re-elected in 1930 . Died . </Td> <Td> (Data unknown / missing .) </Td> </Tr> <Tr> <Td_colspan="2"> Vacant </Td> <Td> April 11, 1932--November 8, 1932 </Td> <Td> (Data unknown / missing .) </Td> </Tr>

How many registered voters in pennsylvania district 18