Table 2.

Life table for survival analysis

Follow-up (years)	Number at start	Withdrawn	Failure	Lost to follow-up	Number at risk	Cumulative success rate	Annual success	Effective no. at risk	95% confidence levels		Confidence diff.
									Upper	Lower	Upper	Lower
0	99	1	0	0	98.5	100.00	100.00	98.50	100.15	96.25	0.15	3.75
1	98	1	2	0	97.5	97.95	97.96	98.00	99.64	92.79	1.69	5.16
2	95	7	0	0	91.5	97.95	100.00	95.73	99.65	92.70	1.70	5.25
3	88	3	0	0	86.5	97.95	100.00	93.24	99.67	92.59	1.72	5.35
4	85	4	0	0	83	97.95	100.00	91.00	99.69	92.50	1.74	5.45
5	81	2	1	0	80	96.70	98.77	88.96	99.15	90.56	2.45	6.14
6	78	7	0	0	74.5	96.70	100.00	86.56	99.18	90.44	2.48	6.26
7	71	4	0	0	69	96.70	100.00	83.89	99.21	90.30	2.51	6.40
8	67	3	0	0	65.5	96.70	100.00	81.35	99.24	90.16	2.54	6.54
9	64	13	1	0	57.5	94.96	98.44	78.11	98.41	87.53	3.45	7.43
10	50	26	0	0	37	94.96	100.00	70.95	98.56	87.02	3.60	7.94
11	24	17	0	0	15.5	94.96	100.00	54.65	99.02	85.46	4.06	9.50
12	7	7	0	0	3.5	94.96	100.00	25.73	101.37	78.81	6.41	16.15