Going from Quarterly to Yearly averages

[#1]

Hi! I have average water level elevation by quarter, but I am trying to get yearly averages. Is there a conditional statement or formula I could use to do this, even if every year doesn't have an even four quarters?

[#2]

If your quarterly water level elevation data is in a single column, then one can use Tables=> Summary to calculate the mean of the quarterly averages.
If your data are laid out with each quarter in a separate column, then you will need to create a new column that has the formula
mean(qt1,qt2,qt3,qt4),
where qt1-qt4 need to be replaced with the actual names of the columns have have the average data.