Name: Average Vertical Speed
Rating: 5 (5 reviews)
Author: danielp27

data field which shows the average accumulated vertical speed, in m/h or feet/h , depending on device settings.
Data can be reset after each lap, by user setting (to be configured within Garmin Connect smartphone app or Garmin express - default: activated)

Discussion: https://forums.garmin.com/showthread.php?366257-Lap-average-vertical-speed
Source code:  https://github.com/danielp27/Lap-average-vertical-speed
all the credit to TRAVIS.VITEK. 
i just uploaded the app
v1.1 add user setting to choose if average vertical speed should be reset on every lap