The following table appears on the CAIN (Conflict Archive on the INternet) web site:						
http://cain.ulst.ac.uk/ni/rel/rel.htm	
Table NI-REL-02: Catholic population in Northern Ireland (units as stated), 1961, 1971, 1981, 1991, and 2001						
Census Year	1961	1971	1981 1	1991	2001	
Total Population 	1,425,042	1,536,065	1,532,196	1,577,836	1,685,267	
No Religion Information 2	26,400	142,500	274,000	174,061	233,853	
Number Stated Catholics 3	497,547	477,921	414,532	605,639	678,462	
% Stated Catholics 	34.90%	31.40%	28.00%	38.40%	40.26%	
Estimated Number Catholics  4 	502,800 5	559,800 6	586,400 7	651,700 8	737,472 9	
Estimated % Catholics 	35.3% 5   	36.8% 6	38.5% 7	41.5% 8	43.76% 9	
% Increase in Catholics	-	1.50%	1.70%	3.00%	2.26%	
Notes:	
1. There was a high level of non-enumeration during the 1981 census mainly due to protests in Catholic areas about the Republican hunger strikes.						
2. Since 1971 there has been a large increase in the number of people who are unwilling to state their religion (during the 1991 census people were also offered the option of answering 'none' to the question on religion in addition to simply not completing the question).						
3. The number of people who were willing to state that they were Catholic represents the absolute minimum figure for Northern Ireland. Adjustments on this baseline figure are required to arrive at a more accurate figure for the total number of Catholics in the region.						
4. Various estimates have been made over the years of the 'true' size of the Catholic population in Northern Ireland.						
5. The estimate for 1961 is simply based on the assumption that 20 per cent of non respondents to the question on religion are Catholic.						
6. The estimate for 1971 is based on Compton, P. (1978) Northern Ireland: A Census Atlas.						
7. The estimate for 1981 is based on Compton, P. and Power, J. (1986) Estimates of the Religious Composition of Northern Ireland Local Government Districts in 1981.						
8. The estimate for 1991 is based on work in progress by Compton, P. and Power, J. being carried out for the Fair Employment Commission (FEC).						
9. The 2001 Census included an additional question about community / religious background which allowed those initially recorded as 'persons with no religion or religion not stated' to be ascribed to the main religious groupings.						
Source:	
Northern Ireland Census 2001 Key Statistics (2002), Table KS07a and Table KS07b.						
Table also available as:	
Rich Text Format (RTF) Document; Microsoft Excel Document