Left-handedness in year-end rankings.

<p>Number of years that individual players were ranked as world no. 1 in (A) men’s (1973–2011) and (B) ladies’ (1975–2011) year-end rankings. Coloured bars denote left-handed players. Note that two female players were listed as world no. 1 in 1995 (Monica Seles and Steffi Graf). Frequencies of (C) male and (D) female left-handed performers in the top 100 (circles) and top 10 (triangles) rankings over time. For men’s tennis, data was fitted to second-order (top 100, <i>R</i>² = .26) and first-order polynomials (top 10, <i>R</i>² = .57), respectively. Blue and red coloured circles indicate a significant (<i>p</i><.05) excess of left-handed players in men’s and ladies’ top 100 rankings, respectively, compared to the normal population. Note that for female professionals, relative frequencies of left-handed players in top 100 rankings are illustrated because of some missing handedness data (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049325#pone.0049325.s001" target="_blank">Table S1</a>). Data of top 10 female players was fitted to a first-order polynomial with <i>R</i>² = .48.