AMC 8 1991 Problem 18

The vertical axis indicates the number of employees, but the scale was accidentally omitted from this graph. What percent of the employees at the Gauss company have worked there for $5$ years or more?

$\text{(A)}\ 9\% \text{(B)}\ 23\frac{1}{3}\% \text{(C)}\ 30\% \text{(D)}\ 42\frac{6}{7}\% \text{(E)}\ 50\%$