finding annual averages using pandas in python

my data looks like this

unit  year   SURQ
10001  2012   89
10002  2012   83
10003  2012   88
10001  2013   75
10002  2013   69
10003  2013   59 
10001  2014   36
10002  2014   59
10003  2014   84

I want to find the annual average values for SURQ by unit. For example average SURQ in 2012 for unit 10001 = ???

I tried using pivot tables

avgSURQ = pd.pivot_table(df,index=['year'])

and groupby

avgSURQ = SURQ.groupby('year')

but I think I am getting the syntax wrong so it doesn't work. I am new to python so I might be misunderstanding the examples online.