Автор: http://www.swissdelphicenter.ch

function CountPos(const subtext: string; Text: string): Integer;
 begin
   if (Length(subtext) = 0) or (Length(Text) = 0) or (Pos(subtext, Text) = 0) then
     Result := 0
   else
     Result := (Length(Text) - Length(StringReplace(Text, subtext, '', [rfReplaceAll]))) div
       Length(subtext);
 end;