Gary Hustwit’s British documentary Helvetica, which tracks 50 years of graphic design history through a debate over the familiar Swiss typeface, became the Gene Siskel Film Center’s all-time box office champion with its June 15-21 run. The film grossed $18,857, substantially more than its runners-up, In Search of Mozart ($11,255) and Bonhoeffer ($10,561). Helvetica is scheduled for a return engagement at Film Center from September 21 through 27.