Table 12
Database	Total sessions	Total sets	Average sets	% on total sets	operator (AND)	Avg. per session	% on total sets for this DB	operator (OR)	Avg. per session	% on total sets for this DB	operator (NOT)	Avg. per session	% on total sets for this DB	
CancerLit	23	118	5,13	1,77	29	1,26	24,58	8	0,35	6,78	0	0	0	
CINAHL	67	531	7,93	7,96	139	2,07	26,18	123	1,84	23,16	0	0	0	
EBM Reviews - Best Evidence <1991 to Present>	49	296	6,04	4,44	67	1,37	22,64	21	0,43	7,09	0	0	0	
EBM Reviews – Cochrane Database of Systematic Reviews	171	831	4,86	12,45	114	0,67	13,72	4	0,02	0,48	0	0	0	
Medline	684	4746	6,94	71,11	1623	2,37	34,2	1382	2,02	29,12	14	0,02	0,29	
Pre-Medline	31	152	4,9	2,28	45	1,45	29,61	21	0,68	13,82	0	0	0	
Total	1025	6674	6,51	100	2017	1,97	30,22	1559	1,52	23,36	14	0,01	0,21