begin{table}[htp]
    centering
    begin{tabular}{
            @{}
           l
            S[group-separator={,}, group-four-digits=true,table-format=5.0]
            S[group-separator={,}, group-four-digits=true,table-format=5.0]
            >{bfseries}S[table-format=3.2, table-text-alignment=center]
            @{}
            }
          toprule
          textbf{Product Group} & textbf{Production Size} & textbf{Number of Failures} & textbf{Failure Rates} \
          & & & textbf{(per 1,000 items)} \
          midrule
          %  addlinespace
          this is foo1 & 11111 & 1111 & 11.11\
          this was foo2 & 22222 & 2222 & 222\
          this will be foo3 & 33333 & 3333 & 3.33\
          foo4 & 44444 & 4444 & 44.4\
          foo5 & 55555 & 5555 & 5.5\
          bottomrule
    end{tabular}
end{table}

... & {textbf{Failure Rates}} \