The territory of Northern Rhodesia was administered by the [British] South Africa Company from 1891 until it was taken over by the UK in 1923. During the 1920s and 1930s, advances in mining spurred development and immigration. The name was changed to Zambia upon independence in 1964. In the 1980s and 1990s, declining copper prices and a prolonged drought hurt the economy. Elections in 1991 brought an end to one-party rule, but the subsequent vote in 1996 saw blatant harassment of opposition parties. The election in 2001 was marked by administrative problems with three parties filing a legal petition challenging the election of ruling party candidate Levy MWANAWASA. The new president launched an anticorruption investigation in 2002 to probe high-level corruption during the previous administration. In 2006-07, this task force successfully prosecuted four cases, including a landmark civil case in the UK in which former President CHILUBA and numerous others were found liable for USD 41 million. MWANAWASA was reelected in 2006 in an election that was deemed free and fair.