(Average Tetrahydrocannabinol (THC), Cannabidiol (CBD), and Cannabinol (CBN) Levels of Seized Samples of Domestic Cannabis in the US, 1995-2008) (see: http://www.drugwarfacts.org/cms/Marijuana#THCTable and http://www.drugwarfacts.org/cms/Marijuana#Potency)




Arithmetic Cannabinoid Averages of Domestic Cannabis Samples by Year Seized
Year	Number of Samples	Percent THC	Percent CBD	Percent CBC	Percent CBN
1988	651	2.56	.43	.14	.14
1989	511	2.00	.59	.12	.08
1990	475	2.58	.67	.19	.03
1991	943	2.57	.87	.21	.03
1992	1025	2.96	.45	.30	.03
1993	1346	2.75	.48	.20	.01
1994	1210	3.02	.50	.25	.02
1995	997	2.93	.41	.25	.03
1996	1025	3.48	.49	.27	.02
1997	1117	3.95	.40	.32	.03
1998	920	3.76	.40	.26	.02
1999	831	4.45	.46	.29	.02
2000	1186	4.10	.33	.26	.06
2001	1007	3.98	.32	.28	.07
2002	701	4.30	.31	.32	.08
2003	625	3.65	.41	.31	.04
2004	694	4.20	.29	.30	.07
2005	657	4.23	.32	.30	.06
2006	778	4.16	.61	.26	.08
2007	882	4.85	.44	.26	.06
2008	653	4.80	.46	.29	.06

Notes:THC = Delta-9-Tetrahydrocannabinol, CBN = Cannabidiol, CBC = Cannabichromene and CBN = Cannabinol.

Source: 

Quarterly Report #104, Dec. 16, 2008 - March 15, 2009, University of Mississippi Potency Monitoring Project (Oxford, MS: National Center for Natural Products Research, a Division of the Research Institute of Pharmaceutical Sciences, 2008), Mahmoud A. ElSohly, PhD, Director, NIDA Marijuana Project (NIDA Contract #N01DA-5-7746), pp. 8 and 10.
https://www.ncjrs.gov/pdffiles1/ondcp/mpmp_report_104.pdf

• THC Potency of Tested Cannabis from Federal Seizure and State and Local Eradication Samples, by Type, 1985-2014
  Year	Non-Domestic Samples (Federal Seizures)						Domestic Samples (State and Local Eradication)
  	Type of Cannabis				All Types1		Type of Cannabis				All Types1
  	Marijuana		Sinsemilla				Marijuana		Sinsemilla
  	Potency2	Number3	Potency2	Number3	Potency2	Number3	Potency2	Number3	Potency2	Number3	Potency2	Number3
  1985	3.44%	745	7.95%	12	3.48%	767	2.19%	703	7.07%	40	2.22%	845
  1986	2.75%	711	8.78%	14	2.80%	753	1.95%	661	8.16%	18	1.84%	803
  1987	3.16%	1,110	8.29%	17	3.20%	1,147	2.46%	441	7.69%	26	2.38%	553
  1988	3.62%	1,127	8.30%	29	3.70%	1,171	2.20%	513	7.33%	69	2.56%	651
  1989	3.68%	725	7.13%	29	3.78%	761	1.71%	350	6.86%	57	2.00%	511
  1990	3.78%	756	9.59%	16	3.82%	788	2.09%	352	10.29%	45	2.58%	475
  1991	3.18%	1,498	11.20%	29	3.26%	1,564	2.90%	651	10.10%	46	2.57%	943
  1992	3.09%	2,461	9.67%	33	3.16%	2,515	3.05%	875	7.72%	43	2.96%	1,025
  1993	3.67%	1,994	4.64%	5	3.65%	2,010	2.83%	1,039	5.82%	118	2.75%	1,346
  1994	3.76%	2,052	6.92%	10	3.75%	2,074	2.95%	980	7.55%	94	3.02%	1,210
  1995	3.95%	3,730	9.64%	17	3.98%	3,747	2.55%	701	7.26%	147	2.92%	999
  1996	4.41%	1,377	11.30%	22	4.51%	1,399	2.90%	767	8.94%	146	3.48%	1,029
  1997	4.93%	1,313	12.02%	18	5.03%	1,331	3.34%	954	11.50%	104	3.99%	1,119
  1998	4.73%	1,298	11.88%	87	4.93%	1,335	3.36%	778	12.58%	64	3.75%	922
  1999	4.36%	1,749	13.49%	55	4.63%	1,804	3.76%	691	13.31%	81	4.43%	833
  2000	5.10%	1,861	12.87%	62	5.35%	1,923	3.96%	1,057	12.72%	51	4.10%	1,185
  2001	5.77%	1,587	12.05%	95	6.13%	1,682	3.58%	805	7.86%	140	3.97%	1,009
  2002	5.66%	1,380	14.41%	302	7.23%	1,682	3.27%	409	7.29%	226	4.29%	703
  2003	5.62%	1,516	14.00%	347	7.18%	1,863	2.38%	377	7.21%	191	3.67%	625
  2004	6.17%	1,418	14.06%	485	8.18%	1,903	2.55%	395	7.67%	246	4.20%	694
  2005	5.92%	1,608	13.04%	681	8.04%	2,289	2.25%	354	7.78%	250	4.21%	656
  2006	6.49%	1,409	13.59%	668	8.77%	2,077	1.99%	362	6.81%	364	4.15%	775
  2007	7.19%	1,303	13.40%	833	9.61%	2,136	1.92%	340	7.21%	503	4.86%	883
  2008	7.16%	1,054	13.08%	942	9.95%	1,997	1.82%	302	7.53%	370	4.84%	701
  2009	7.13%	1,026	12.36%	1,043	9.75%	2,069	2.43%	435	7.37%	490	4.89%	962
  2010	6.68%	893	12.80%	1,363	10.36%	2,256	2.79%	290	11.84%	97	4.89%	405
  2011	5.60%	722	13.64%	1,615	11.13%	2,337	NA	0	NA	0	NA	0
  2012	6.12%	546	14.48%	1544	12.29%	2,052	NA	0	NA	0	NA	0
  2013	6.31%	262	13.64%	923	11.99%	1,185	NA	0	NA	0	NA	0
  2014	6.13%	123			12.17%		NA	0	NA	0	NA	0

  Notes:
  No data -- beginning in 2011, no domestic samples were tested.
  1 The category "All Types" of cannabis tested includes ditchweed and a small number of Thai sticks.
  2 These percentages, indicating potency, are based on simple arithmetic means calculated by dividing the sum of the delta-9THC concentrations of each sample by the number of seizures and are not normalized by weight of seizure.
  3 Number of tested samples that yield the potency in prior column.
  4 Data for 2014 are preliminary

  Source: 

  "National Drug Control Strategy Data Supplement 2015," Executive Office of the President, Office of National Drug Control Policy, November 2015, Table 78, p. 92, citing as its sources: University of Mississippi, National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences. Quarterly Report #129, Potency Monitoring Program July 13, 2015) for data from 1995 to 2014; Quarterly Report 107 (January 12, 2010) for data from 1985 to 1994.
  https://www.whitehouse.gov//sites/default/files/ondcp/policy-and-research/2015_data_supplement_final.pdf

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