Wrong percentage in Host State Breakdowns

Hi I am new here and this is my first post.

I am using Nagios 2.8 and I have problem with Host Availability Report.

Problem appeared when I tried to schedule host downtime.

I added one host for test purposes. I have scheduled downtime and after three days when I tried to get Availability Report I have noticed that statistic is wrong.
As you can see from attached table in last column added values are greater then 100% and one value is negative!!!

Can anyone give me any idea what is going on!!!???

Just to stress statistics for other hosts are OK but also downtime wasn’t scheduled.
Also availability reports for services shows correct statistics.