The reason for the discrepancy is because the VSWR graph shows the best-case free space VSWR and the table shows expected VSWR.
If the antenna is placed on a thin sheet of plastic with the cable straight with no bends you should be able to achieve the VSWR in the graph. That is the ideal placement for the antenna.
When the antenna is mounted to a thick plastic housing surrounded on all sides and next to a solid copper PCB, battery or LCD the VSWR of the antenna will degrade.
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