Table 12. Numbers of papers according to the rigor-ranking scores in identified periods.

Ranking rigor	Low ranking [1; 7) (A/B/C)	Middle ranking [7; 14) (A/B/C)	High ranking [14; 22) (A/B/C)
Low rigor [2; 4) (A/B/C)	1/1/0	0/0/0	0/0/0
Middle rigor [4; 6) (A/B/C)	4/11/0	0/4/9	0/0/0
High rigor [6; 9] (A/B/C)	2/11/0	0/3/19	0/0/2