how many swimmers swam the 100 meters in under 55 seconds?
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col : rank | name | nationality | time row 1 :  | mark henderson | united states | 54.11 row 2 :  | eduardo piccinini | brazil | 54.63 row 3 :  | brian alderman | united states | 54.75 row 4 : 4 | francisco sánchez | venezuela | 54.99 row 5 : 5 | edward parenti | canada | 55.23 row 6 : 6 | diego cuenca | colombia | 55.67 row 7 : 7 | josé meolans | argentina | 55.91 row 8 : 8 | ruben calderon | el salvador | 56.04
how many swimmers swam the 100 meters in under 55 seconds?
Rank Name Nationality Time
Mark Henderson United States 54.11
Eduardo Piccinini Brazil 54.63
Brian Alderman United States 54.75
4 Francisco Sánchez Venezuela 54.99
5 Edward Parenti Canada 55.23
6 Diego Cuenca Colombia 55.67
7 José Meolans Argentina 55.91
8 Ruben Calderon El Salvador 56.04
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