Table 2. Intraoperative and Postoperative data according to patients’ group.

	Group 1 (1–15)	Group 2(16–30)	Group 3 (31–45)	Group 4 (46–60)	Group 5(61–75)	Group 6(76–90)	Group 7(91–105)	Group 8(106–120)	Group 9(Senior surgeon)	P
Multiple access(N,%)	1(6.7%)	1(6.7%)	3(20%)	2(13.3%)	2(13.3%)	1(6.7%)	1(6.7%)	2(13.3%)	2(13.3%)	0.952
Hb drop(g/dl)	2.53±1.91	4.20±2.11	3.53±1.77	2.73±1.74	2.53±2.19	2.47±1.49	2.60±1.77	2.33±1.78	2.53±1.91	0.071
Stone free rate (N, %)	9(60%)	10(66.7%)	12(80.0%)	10(66.7%)	11(73.3%)	12(80.0%)	12(80.0%)	14(93.3%)	12(80.0%)	0.714
CIRF rate	4(26.7%)	3(20.0%)	2(13.3%)	3(20%)	2(13.3%)	3(20.0%)	2(13.3%)	0	3(20.0%)	0.852
Hospital stay(day)	3.5±0.98	4.1±0.96	3.4±0.95	3.67±0.8	3.60±0.88	3.33±0.62	3.67±0.76	3.73±0.78	3.53±0.98	0.196

Data are presented as mean (SD) except access number, stone free rate and CIRF rate which are presented as n (%).CIRF clinical insignificant residue fragment.