Table 4. Publication bias of studies examined with Begger test.

		Begger				Begger
Time	No. studies	Z	P	Years post-interruption	No. studies	Z	P
1992	1	NA		1	1	NA
1993	1	NA		2	2	1.00	0.32
1994	2	1.00	0.32	3	3	0.52	0.60
1995	5	0.00	1.00	4	2	1.00	0.32
1996	7	-1.05	0.29	5	3	-1.57	0.12
1997	8	0.49	0.62	6	2	1.00	0.32
1998	7	0.19	0.85	7	1	NA
1999	9	1.04	0.30	8	1	NA
2000	7	1.65	0.10	9	4	1.36	0.17
2001	8	0.45	0.65	10	8	-0.49	0.62
2002	7	0.75	0.45	11	8	-0.25	0.81
2003	9	0.21	0.84	12	9	0.83	0.40
2004	10	0.80	0.42	13	9	-0.25	0.81
2005	13	0.69	0.49	14	13	1.22	0.22
2006	16	0.63	0.53	15	13	0.61	0.54
2007	14	0.05	0.96	16	14	0.61	0.54
2008	20	0.72	0.47	17	8	0.99	0.32
2009	13	0.41	0.68	18	9	0.25	0.81
2010	9	1.98	0.05	19	8	1.24	0.22
2011	7	1.05	0.29	20	7	0.15	0.88
2012	3	0.52	0.60	21	9	0.74	0.46
2013	1	NA		22	7	1.35	0.18
				23	11	0.45	0.66
				24	7	-0.75	0.45
				25	4	0	1
				26	4	0.68	0.50
				27	4	1.57	0.12
				28	3	1.00	0.32
				29	1	NA
				30	1	NA
				31	1	NA