Centers of exceptional Lie groups
It is commonly say the Lie groups of given exceptional Lie algebra $\mathfrak{g}_{2}$, ${\mathfrak {f}}_{4}$,${\mathfrak {e}}_{6}$, ${\mathfrak {e}}_{7}$, ${\mathfrak {e}}_{8}$ are $G_2$, $F_4$, $E_6$, $E_7$, $E_8$. What the centers $Z(G)$ of these Lie groups $G$?
Note that: In a previous question, I also asked whether there are more and different Lie groups of the same exceptional Lie algebra? for $\mathfrak{g_2,f_4,e_6,e_7,e_8}$. See https://en.wikipedia.org/wiki/Exceptional_Lie_algebra and Different Lie groups of the same exceptional Lie algebra? for $\mathfrak{g_2,f_4,e_6,e_7,e_8}$