In North America there are about four or five major tank car builders. The total capacity could be around—and here I'm just going with rough numbers—maybe 20,000 per year.
Just another number, maybe it's interesting to you.... On some other issues we mentioned here, just to give you some numbers, between 2003 and 2012 it's recorded that there have been 14,229,880 tank car shipments just in North America. These are not my data, this is from RSI. It has only recorded 508 individual accidents causing major problems.
Don't go with my numbers, I suggest you look at it. I'm saying that because if you look at the global system in transportation we have on water, in the sky, on rail, on road, and if you want to categorize the efficiency of each of them in big numbers, you can see that after water is railroad. That's the highest efficiency you get.