Initial depth and behavior
											100 m												150 m											200 m
			Start time					passive							fixed- depth						passive					fixed- depth					passive						fixed- depth
			1 May						45.7 %							35.7						55.8					82.1					57.9						89.6
			1 July							52.7						44.4						63.4					81.9					64.0						85.4
			1 Sept							61.8						56.1						73.8					80.3					72.5						85.0
			A four month difference in entry time changes retention by at most about 20%