Read the following passage and answer the questions given below:
Considering the latitudinal distribution of animal husbandry in the world, it is located between 30°N to 60°N and 30°S to 55°S latitudes.
Climate is one of the most influencing factors in the development of animal husbandry. It is more developed in the Northern Hemisphere. Presence of grasslands in Australia and North and South America has led to the distribution of this occupation. But, this occupation is influenced by advanced technology, market, and availability of large estates.
It has developed on a commercial basis in North America, South America, and Australia. The animal husbandry in North and South America is carried out with the help of advanced technology on a commercial scale.
Dense forests, inhospitable climate, low-quality fodder in the equatorial region has discouraged the development of animal husbandry in these regions.
The table shows the data of running a machine for five years. The original machine cost is Rupees 70,000. In order to minimize the average total cost per year for running the machine, the machine should be replaced after ............. years. (Answer in integer) 