how many nations are shown?
chinese taipei (tpe), russia (rus), great britain (gbr), slovakia (svk), china (chn), mexico (mex), germany (ger), south korea (kor), switzerland (sui), thailand (tha), uzbekistan (uzb)
of those which have silver medals?
slovakia (svk), china (chn), mexico (mex)
which of those only has one silver medal?
mexico (mex)