Obtain the trend value for the following data using 4-yearly centered moving averages :
\[
\begin{array}{|c|c|c|c|c|c|c|c|c|c|c|}
\hline
\mathbf{Years} & 1976 & 1977 & 1978 & 1979 & 1980 & 1981 & 1982 & 1983 & 1984 & 1985 \\
\hline
\mathbf{Index} & 0 & 2 & 3 & 3 & 2 & 4 & 5 & 6 & 7 & 10 \\
\hline
\end{array}
\]