Table 4.

Overall similarity index of included articles (n=495)

Overall similarity index	No of articles (%)
0–10%	137 (28)
11–20%	202 (41)
21–30%	104 (21)
31–40%	34 (7)
41–50%	13 (3)
51–60%	2 (0.4)
61–70%	3 (0.6)
71–100%	0