Duration (minutes)	Return period (years)
Duration (minutes)	5	10	25	50	100
5	123	155	180	213	269
10	102	130	150	177	224
20	77	97	113	133	168
30	61	78	90	106	134
60	38	49	56	66	84
90	28	35	41	48	61
100	26	32	38	44	56