The ornamental design for table base, as shown and described.
FIG. 1 is a perspective view of the table base embodying my new design;
FIG. 2 is a front view thereof, the rear view being a mirror image thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof; and,
FIG. 5 is a right side elevational view thereof, the left side elevational view being a mirror image thereof.
FIGS. 1-5 show portions of the table base in phantom lines. The phantom line portions are shown for environmental purposes and form no part of the claimed design.