I've just checked it in the Ford Service Manual:

Quote:

The normal range of the throttle angle measurement for the Throttle Position (TP) sensor is 0 to 85 degrees.


The graph they give shows that 0 to 15 degrees is considered IDLE and 76-94 degrees is considered WOT.

If 85 is 100% then 20% is 17 and 19% is 16.15 so indeed is's slightly high, but it's nothing to worry about.
If you want, replace it for your peace of mind, it costs about $20-25 and easy to replace unless you have a 95-97 Zetec.

Tiv