A strain I never heard of hit the #4 spot in popularity. Complete surprise, since the list seems to rarely move out of the strains that continually hit the top 10 or 15. With legalization rolling out in the northeast states, I noticed that Sour Diesel is finally trending down in a serious way. That strain got it's claws into the NYC area in the 90's and spread like a wild fire... to the point where people just expected their dealer to carry Sour Diesel. I think Blue Dream will always stay in the top 10 to 15 for a very long time. It's the strain that's very friendly for people trying weed for the first time, so dispensaries often suggest that.