WR is up at 22%, but as someone else said, THC % doesnt mean sweet fuck all.

You have to concider the CBD and CBN % as well, and also, the growing conditions play a major part on the plants resin production.

The strongest strain ever found in the world was found in England this year, being grown by a retired bloke, i think it was in the Midlands.



Afgan
Northern Lights
White Widow
White Rhino
Hash Plant

Grown properly these are some of the strongest strains.

But remember, if you want the most potent strain you can find, dont boher with sativas, indicas are known to have a higher resin production, with a higher concentration of THC and CBD's.

Indicas are also best for making hashish.