 In multi-member elections, when the exact number of participating voters is unknown, this is calculated by dividing the number of votes by four (to 1868), three (1868–1885) and two thereafter.To the extent that electors did not use all their votes this will be an underestimate of turnout.Where a party had more than one candidate in one or both of a pair of successive elections change is calculated for each individual candidate, otherwise change is based on the party vote.