Stephen Clarkson (2005) shows how the Liberal Party has dominated all the party systems, using different approaches. It began with a "clientelistic approach" under Laurier, which evolved into a "brokerage" system of the 1920s, 1930s and 1940s under Mackenzie King. The 1950s saw the emergence of a "pan-Canadian system", which lasted until the 1990s. The 1993 election – categorized by Clarkson as an electoral "earthquake" which "fragmented" the party system, saw the emergence of regional politics within a four party-system, whereby various groups championed regional issues and concerns. Clarkson concludes that the inherent bias built into the first-past-the-post system, has chiefly benefited the Liberals.