Lead time percentage calculate

Hi experts:

12.1.2

Routing set up as following:

1. All resources are available 24 hours

2. department01 seq=10 resource01  uom=min  basis=item  usage=20  assingned  units=1  schedule=yes
department02 seq=10 resource02  uom=min  basis=lot   usage=30  assingned  units=2  schedule=yes
department03 seq=10 resource03  uom=min  basis=item  usage=100 assingned  units=4  schedule=prior
department03 seq=20 resource04  uom=min  basis=item  usage=50  assingned  units=5  aschedule=yes

3. Run 'Calculate Manufacturing Lead Times GUI ' for this routing, result as following:

Seq      Leadtime%

10            0

20           94.38

30           92.13

40           97.75

How is the leadtime calculate?

Thanks

Fengling