IP Address Pool

On my DHCP server I have addresses 172.17.196.23 – 172.17.196.114 up for allocation in the IP Address Pool. In DHCP it constantly shows we are near to running out of IPs, and this is causing people difficulty logging onto the network in the morning. When I view the stats for the Scope, it says I have 89 IPs and 89 IPs are in use, but when I actually count all of the IPs used under Address Leases, there are only around 40 in use.

Why is this saying I have run out of IP addresses when there should be plenty left? Do you know how to fix this?

Thanks for any help you can give me.