CAMBODIAN rubber prices have increased about five per cent over the past year, according to Cambodian  Rubber Association president Mak Kim Hong. Top-quality rubber sold for US$4,700 a tonne at the weekend, compared with $4,475 a tonne at this time last year.  “Now there’s high demand for rubber on the international market, especially from China.  We mostly export our rubber to China,” Mak Kim Hong said. “This is the time to invest more in the sector.” Mak Kim Hong, who is also the director-general of Chub Rubber Plantation, said his company aimed to export about 10,000 tonnes of rubber to China this year.