service's sinking of the Rainbow Warrior, and the diplomatic ramifications following the incident, did much to promote the anti-nuclear stance as an important symbol of New Zealand's national identity. Continuing reform under National Voters unhappy with the rapid speed and far-reaching extent of reforms elected a National government in 1990, led by Jim Bolger. However the new government continued the economic reforms of the previous Labour government, in what was known as Ruthanasia. Unhappy with what seemed to be a pattern of governments failing to reflect the mood of the electorate, New Zealanders in 1992 and 1993 voted to change the electoral system to mixed-member proportional (MMP), a form of proportional representation. New Zealand's first MMP election was held in 1996. Following the election National was returned to power in coalition with the New Zealand First party. With the end of the Cold War in 1991, the nation's foreign policy turned increasingly to issues of its nuclear-free status and other military issues, its adjustment to neoliberalism in international trade relations, and its involvement in humanitarian, environmental and other matters of international diplomacy. 21st century In the 21st century, international tourism was a major contributor to the New Zealand economy, until it was brought almost to a halt by the COVID-19 pandemic in 2020, and the service sector more generally has grown. Meanwhile, the traditional agricultural exports of meat, dairy and wool have been supplemented by other products such as fruit, wine and timber as the economy has diversified. 2000s and 2010s The Fifth Labour Government led by Helen Clark was formed following the December 1999 election. In power for nine years, it maintained most of the previous governments' economic reforms – restricting government intervention in the economy much more so than previous governments – while putting more emphasis on social policy and outcomes. For example, employment law was modified to give more protection to workers, and the student loan system was changed to eliminate interest payments for New Zealand resident students and graduates. New Zealand retains strong but informal links to Britain, with many young New Zealanders travelling to Britain for their "OE" (overseas experience) due to favourable working visa arrangements with Britain. Despite New Zealand's immigration liberalisation in the 1980s, Britons are still the largest group of migrants to New Zealand, due in part to recent immigration law changes that privilege fluent speakers of English. One constitutional link to