I don't have the article now, I read it years ago, but here's part of the Wiki on it. You can do some personal digging and find it, I am too lazy. Interesting, it was actually 95%, not 80%. The article I read stated a little over 80%. Hm.
United States: 1970 to the present
American LSD usage declined in the 1970s and 1980s, then experienced a mild resurgence in popularity in the 1990s. Although there were many distribution channels during this decade, the U.S. DEA identified continued tours by the psychedelic rock band The Grateful Dead and the then-burgeoning rave scene as primary venues for LSD trafficking and consumption. American LSD usage fell sharply circa 2000, following a single major DEA operation.
Pickard and Apperson
The decline is attributed to the arrest of two chemists, William Leonard Pickard, a Harvard-educated organic chemist, and Clyde Apperson. According to DEA reports, black market LSD availability dropped by 95% after the two were arrested in 2000. These arrests were a result of the largest LSD manufacturing raid in DEA history.
Pickard was an alleged member of the Brotherhood of Eternal Love group that produced and sold LSD in California during the late 1960s and early 1970s. It is believed he had links to other "cooks" associated with this group — an original source of the drug back in the 1960s — and his arrest may have forced other operations to cease production, leading to the large decline in street availability.
The DEA claims these two individuals were responsible for the vast majority of LSD sold illegally in the United States and a significant amount of the LSD sold in Europe, and that they worked closely with organized traffickers. While this claim may have some bearing, the extent of Pickard's direct influence on the overall availability in the United States is not fully known. Some attest that "Pickard's Acid" was sold exclusively in Europe, and was not distributed through American music venues.
In November of 2003, Pickard was sentenced to life imprisonment without parole, and Apperson was sentenced to 30 years imprisonment without parole, after being convicted in Federal Court of running a large scale LSD manufacturing operation out of several clandestine laboratories, including a former missile silo near Wamego, Kansas.
Gel tabs are the awesomose( i don't care if that is not a real word}, the greatest time I have ever had was on black gel tabs. I saw a single thunder cloud rain down on a music festival while I stood in a field watch the lighting and rain pour down on them and I was only a couple hundred yards away not getting rained on. The cloud interupted me arranging how the stars should be.
I am pretty sure there is no difference based on the color of the gel tabs but I always had a great trip on the dark green gels, the blue and purples started slow and the peak always creeped up on me.....