The following table appears on the CAIN (Conflict Archive on the INternet) web site:

http://cain.ulster.ac.uk/ni/security/security.htm

Table NI-SEC-03: British Army Personnel (number) in Northern Ireland, 1969 to 2005 (incomplete)
Year British Army Total British Regiments UDR / RIR Total UDR / RIR Full-Time UDR / RIR Part-Time
1969 (Jun)

2700

2700

     
1970 (Jan)

8100

6300

1800

   
1971

11800

7800

4000

   
1972

22800

14300

8500

   
1972 (Jul)

30300

21800

8500

   
1973 (Jan)

26000

16900

9100

   
1974

23900

16200

7700

   
1975

22700

15000

7700

   
1976

22800

15100

7700

   
1977

21900

14300

7600

   
1978

22200

14400

7800

   
1979

21200

13600

7600

   
1980

19300

11900

7400

   
1981

19100

11600

7500

   
1982

18011

10900

7111

2793

4318

1983

17125

10200

6925

2690

4235

1984

16468

10000

6468

2689

3779

1985

16194

9700

6494

2755

3739

1986

16908

10500

6408

2672

3736

1987

17931

11400

6531

2785

3746

1988

17593

11200

6393

2858

3535

1989

17430

11200

6230

2947

3283

1990    

6043

2955

3088

1991    

6276

3277

2999

1992

17417

12000

5417

2797

2620

1993    

5412

2902

2510

1994 (Jul)

19500

 

5241

2956

2285

1995          
1996          
1997          
1998

15500

10500

5000

3000

2000

1999

15500

11150

4350

2500

1850

2000 (Jun)

13500

       
2001

13000

       
2002
13681
       
2003
13311
       
2004
12658
       
2005 (31 Jul)
10083
       
Planned Troop Levels 1
2006 (31 Mar)
9200
       
2007 (31 Mar)
8500
       
2007 (31 Jul)
5000
       
Notes:
1. The MOD confirmed on 28 March 2006 the major troop reductions to the planned level of no more than 5,000 by 31 Jul 07.
UDR - Ulster Defence Regiment (A regiment of the British Army recruited in Northern Ireland, 1 April 1970 to 1 July 1992)
RIR - Royal Irish Regiment (Established from the merger of the UDR and the Royal Irish Rangers on 1 July 1992)
This information on British Army troop levels is incomplete, it is hoped to be able to complete the table in the future.
Sources:
Hadfield, B. (ed.) (1992) 'Northern Ireland: Politics and the Constitution'. Buckingham: Open University Press.
Ireland Almanac and Yearbook of Facts, 1997, 1998, 1999, 2000
Northern Ireland Annual Abstract of Statistics, 1994
Various press reports.
Table also available as:
Rich Text Format (RTF) Document; Microsoft Excel Document