Who achieved a higher ranking in professional tennis,  Zheng Jie and Jonas Björkman?
Zheng Jie:  Her career-high singles ranking is World No. 15 which she achieved on 18 May 2009. Jonas Björkman: Jonas Lars Björkman (] ; born 23 March 1972, Alvesta, Sweden) is a former World No. 4 Swedish professional tennis player.
i don't know