A firm hires employees at five different skill levels P, Q, R, S, T. The shares of employment at these skills levels of total employment in $2010$ is given in the pie chart as shown. There were a total of $600$ employees in $2010$ and the total employment increased by $15\%$ from $2010$ to $2016$. The total employment at skill levels P, Q and R remained unchanged during this period. If the employment at skill level S increased by $40 \%$ from $2010$ to $2016$, how many employees were there at skill level T in $2016$?
1. $30$
2. $35$
3. $60$
4. $72$