If you find you're >5.5 start contacting the World Tour teams.

The plot below has the 50 percentile at somewhere between 3.6-3.7 (if I'm reading the chart correctly) and the same for men and woemen. And this seems a little on the high side to me for both genders. So I take the percentiles here with a grain of salt.
From cyclinganalytics.com





Here is a plot of selected TrainerRoad users from 2014. Assume (1) if you're on TrainerRoad you're fairly serious about cycling (2) people accurately report their weight on TrainerRoad. Here the average FTP is ~3 with ~1000 data points although results for men and women might be mixed together here. I think this corresponds with some aggregated data w/kg FTP on the Garmin web site as well.