Oxygen (
O
) has three naturally occurring isotopes:
16
O
,

17
O
,
and
18
O
.

16
O
is the most abundant isotope with an abundance of
99.757
%
and an isotopic mass of
15.995
u.
The second most abundant isotope is
18
O
with an abundance of
0.205
%
and an isotopic mass of
17.999
u.
The least abundant isotope,
17
O
,
has an abundance of only
0.038
%
and an isotopic mass of
16.999
u.

Calculate the average atomic mass of oxygen.