A corporation's pension plan provides a lifetime annual income to its employees upon retirement at age $65.$ The plan provides $2\%$ for each year of service of the employee's salary upon retirement. Those who retire before $65$ have their benefit reduced by $1\mathrm{.}6\%$ for each year before $65$ that they retire. Russ retires at age $62$ with $15$ years of service. If his salary upon retirement is $$51,091,$ what is his annual pension benefit?