What is the ratio of actual flight time to simulator time on type for airline pilot training?
Zero hours in type.

The first time a new FO flies the actual airplane could be their first revenue flight with a training captain in the left seat.  Technically, these flights are still considered training, specifically "initial operating experience" (IOE) and a few trips will be flown with training captains before the new FO is released to fly with regular line captains.  IOE is conducted on revenue flights though, so its entirely possible that the before your flight leaves the gate that the FO has exactly 0 hours in type.

The initial training (leading to either a full type or an SIC type) and the upgrade training (full type ride if you only had an SIC type) are 100% in FTD and level D FFS (full flight simulators) and the checkride is in the FFS.