As you can see from the chart above, Katie Couric’s first nine months at CBS aren’t exactly going as planned – in fact, she’s costing CBS an arm and a leg and a whole lot more for each viewer she hangs onto in her shrinking audience.

And last week the $15 million- a-year anchor got even more expensive.

When the ratings for “The CBS Evening News” dipped to 5.9 million for the week ended May 25 – an all-time low, and a smaller audience than former anchors Dan Rather and Bob Schieffer ever saw – it meant

CBS was paying $2.51 per viewer.

By comparison, ABC’s Charlie Gibson-anchored “World News Tonight,” cost 89 cents per viewer (7.78 million tuned in), while NBC’s “Nightly News” with Brian Williams was a relative bargain at about 55 cents per head. Gibson reportedly pulls down about $7 million a year, and Williams is paid an estimated $4 million.

In happier days, CBS was paying interim anchor Schieffer 48 cents per viewer (7.2 million viewers, $3.5 million estimated salary) while Rather’s cost per head came in at about a buck – 7 million viewers, $7 million annually. In fact, after attracting a surprising 13.6 million viewers for her debut telecast last September, Couric has lost more viewers than Rather usually attract-