Read the passage and answer the questions that follow. Given the precarious…

Read the passage and answer the questions that follow.

Given the precarious condition of its ground and surface water resources (rivers, streams, lakes, wetlands and reservoirs), India could be a water-scarce country in the next 40 years. With 1,486 cubic metres (~1.5 million litres) of water available per person per annum, India falls in the water-stressed category. A dip below 1,000 cubic metres per person per annum will push it into the water-scarce category.

The manner of water consumption also compounds the problem. Central Ground Water Board (CGWB) statistics show that indiscriminate use of groundwater turned 4% of the country’s 7,089 assessed units critical in 2022, while 14% were assessed as over-exploited. The situation was worse in 2017, when 17% of the units were over-exploited. Various recharge and conservation efforts have borne fruit, but the number of such units remains high in states such as Punjab, Rajasthan, Haryana, Delhi, Tamil Nadu and Karnataka.

In India, 87% of groundwater is extracted for irrigation, and experts say excess withdrawal throughout the year may be the biggest reason for depletion, as recharge primarily happens during the monsoon. On the other hand, encroachment of water bodies and the discharge of untreated wastewater into rivers and streams have reduced surface-water resources.

Assuming that the total number of groundwater units assessed by CGWB in the years 2017 and 2022 were the same (i.e. 7,089), what is the difference between the number of over-exploited units in 2017 and 2022?