rank nation gold silver bronze total
rank
nation
gold
silver
bronze
total
number
number
number
number
number
number text number number number number
1 united states 5 6 5 16
how many nations won at least two gold medals ?
WRB JJ NNS VBD IN JJS CD NN NNS .
3
select count ( c2 ) from w where c3_number >= 2