SanDisk SSD U100 128GB - SMART data and lifetime

I found the claimed endurance* for this model to be 80 TBW.
* http://www.sandisk.com/products/ssd/sata/u100/#Specifications

So (correct me if I am wrong), with
“Sector Size: 512”
“Total_LBAs_Written: 4078956678”
That would mean I have only used about 2.3% of the 80 TBW.
(4078956678 * 512) / (1024 ^ 4) ~= 1.9TB
and (1.9/80)*100 ~=2.3%

If anyone could confirm that is a proper way of estimating the
remaining lifetime of this SSD, I would be gratefull.

Thanks and regards.