Here are the Season Ratings/Rankings from 18th September 2006 - 4th March 2007. I've highlighted Lost, 24 and Heroes for comparison.
I. T. R. S.
RANKING REPORT
01 THRU 185 (OUT OF 185 PROGRAMS)
DAYPART: PRIMETIME MON-SUN
FROM 09/18/06 THROUGH 03/04/07
REGULAR PROGRAMS
LIST RANKED BY: VIEWR 2+ (000)
STD RANKINGS WE 3.4.07
Source: ABC Medianet