i was have same problem here too but as i Google for solution i saw this post under the search result and it just answer my question thanks for this post.
beginCount = 0;
stopCount = 100;
beginTime = 0; // start counting at time = 0
countDur = 4; // count for 4 seconds
"" + Math.round(linear(time,beginTime,beginTime + countDur,beginCount,stopCount)) + "%"