1996 National Household Survey on Drug Abuse:  Preliminary Results

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70617 (204A)             PRELIMINARY DATA - AS OF JUNE 1997 

Table 39. Estimated Number (in Thousands) of Persons Who First Used Marijuana During Each Year1962-1995, Their Mean Age at First Use, and Annual Age-Specific Rates of First Use (per 1000Person-Years of Exposure), Based on 1994-1996 NHSDAs




AGE-SPECIFIC RATE OF FIRST USE1

YEAR

INITIATES

(1000s)

MEAN

AGE

12-17

18-25

26-34

1962

68

*

0.3

3.0

0.2

1963

171

22.4

3.0

2.1

3.3

1964

289

18.1

5.3

6.7

1.2

1965

630

19.7

8.1

14.4

5.9

1966

905

19.8

12.2

23.8

0.3

1967

1592

20.1

15.6

44.3

7.8

1968

1537

19.3

18.6

41.6

3.5

1969

2361

19.4

32.8

58.2

5.4

1970

2796

19.1

37.1

68.2

10.1

1971

2867

18.7

42.1

68.6

14.8

1972

2845

18.3

48.1

66.1

8.0

1973

2843

17.9

57.8

59.7

7.0

1974

2875

18.5

53.1

62.6

7.9

1975

3001

18.5

68.4

49.3

11.7

1976

2818

18.8

61.1

53.4

10.5

1977

2808

19.1

65.5

47.7

9.4

1978

2912

18.0

75.1

52.7

7.7

1979

2553

17.5

65.6

54.6

3.2

1980

2600

18.7

60.8

59.5

5.7

1981

2066

17.5

56.4

40.7

3.6

1982

2065

17.7

55.0

42.6

7.0

1983

2066

17.6

54.7

43.6

4.0

1984

1962

19.7

49.3

38.9

4.6

1985

1827

17.5

53.2

39.0

2.0

1986

1884

20.1

49.7

42.8

2.9

1987

1817

17.6

49.7

44.2

2.5

1988

1560

17.3

44.1

39.2

1.3

1989

1370

17.5

36.2

34.8

2.8

1990

1446

17.3

39.1

37.8

1.5

1991

1432

17.1

39.2

36.3

1.2

1992

1715

17.8

45.8

41.4

1.9

1993

1987

16.9

56.5

46.4

2.3

19942

2400

16.7

74.7

48.9

3.5

19953

2368

16.7

75.7

47.7

3.3

*Low precision; no estimate reported.

**Estimate rounds to zero.

1The numerator of each rate equals the number of persons who first used the drug in the year (times 1000). The denominator of each rate equals the number of persons who were exposed to risk of first use during the year, weighted by their estimated exposure time measured in years. For example, for the age group 12-17 in 1990, the denominator is the sum of three components:

(1)those persons 12-17 years old in 1990 who first used the drug in 1989 or earlier, times a weight of zero. The weight is zero since they had zero exposure to the risk of first use in 1990.

(2)those who first used the drug in 1990 times a weight of .5. The weight of .5 assumes that these people, on average, first used the drug at midyear and consequently have a half year of exposure (i.e. the first half of the year.)

(3)those who never used, or those who first used the drug in 1991 or later, times a weight of one. The weight of one assumes their exposure to the risk of first use during 1990 was for the whole year.

Each person is also weighted by his/her sample weight.

2Estimated using 1995 and 1996 data only.

3Estimated using 1996 data only.

Source: SAMHSA, Office of Applied Studies, National Household Survey on Drug Abuse, 1994-1996.

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