Because from that, you can figure out suppose you say that the ship roll exceeds 10 degrees and you say that if it exceed 10 degree, you cannot do an operation. So, you can find out the down time in offshore structure if it, heave is more than certain time says four meter then it cannot operate. So, you find out that the chances in this sea, in a long term that the heave will exceed 4 meter is equal to 20 percent. So, you say I have 80 percent you know operation time, 20 percent down time like that we go.