In Monitoring -> Graphs (select a pie chart) if both values are equal (for example total space and free space), then one value is 100%, but second value is 100.00%. See attached image.
Decimals should be used only if value is fractional.
To reproduce, use attached sql dump. And then in Monitoring => Graphs => Group: Zabbix servers; Host: Zabbix servers; Graph: Swap usage