<Table> <Tr> <Th> use </Th> <Th> PbO (wt.%) </Th> </Tr> <Tr> <Td> Household "crystal" leaded glass </Td> <Td> 18--38 </Td> </Tr> <Tr> <Td> Ceramic glazes and vitreous enamels </Td> <Td> 16--35 </Td> </Tr> <Tr> <Td> High refractive index optical glasses </Td> <Td> 4--65 </Td> </Tr> <Tr> <Td> Radiation shielding </Td> <Td> 2--28 </Td> </Tr> <Tr> <Td> High electrical resistance </Td> <Td> 20--22 </Td> </Tr> <Tr> <Td> Glass solders and sealants </Td> <Td> 56--77 </Td> </Tr> </Table> <Tr> <Th> use </Th> <Th> PbO (wt.%) </Th> </Tr> <Tr> <Td> Household "crystal" leaded glass </Td> <Td> 18--38 </Td> </Tr> <Tr> <Td> Ceramic glazes and vitreous enamels </Td> <Td> 16--35 </Td> </Tr>

When did they stop using lead in crystal