Table 1. Frequencies of all matches and retired matches by surface type. Surface All matches Retired matches Retired matches in % Carpet 34,375 641 1.86 Clay 197,543 5,484 2.78 Grass 23,212 382 1.65 Hard 163,803 4,284 2.62 Unknown 1,556 10 0.64 Total 420,489 10,801 2.57