set timefmt "%m/%d/%Y"                                                  
set xdata time
set key outside below
plot \
        "a.tsv" using 1:4 title "128", \
        "a.tsv" using 1:5 title "440", \
        "a.tsv" using 1:6 title "1024", \
        "a.tsv" using 1:7 title "Mixed"