how to understand burst sizes info from profiler

1. Why Bandwidth is 0.1MB/s??Is there something wrong with profiler? I also encounter this problem in quartus 17.0

2. I have my kernel code like

typedef struct{

float a[20];

}A

__kernel foo(__global *A data){

A localdata[100];

for(i=0;i<100;i++){

localdata[i]=data[i+index];

}

}

I expect every memory access will bust coalescing read global memory for 20 float, so Average Burst Size suppose larger than 1.

but in profiler Average Burst Size shows only 4~6. how to increase my access efficiency?