A porch light is left on all the time. The light bulbs used by the homeowner have an exponential lifetime with a mean of 2 years. When one lightbulb goes out, it is immediately replaced. What is the probability that we will have to replace a lightbulb during the next calendar year? Given that we change light bulbs exactly once during the next calendar year, what is the probability that we will have to change lightbulbs exactly two times during the following calendar year?