The three pie charts below show the changes in annual spending by a particular UK school in 1981 1991 and 2001 Summarise the information by selecting and reporting the main features and make comparisons where relevant

The pie charts illustrate how a UK school spent on different running costs in three years, 1981, 1991, and 2001.
Overall, it is clear that the highest expenditure was on staff salaries. While the spending on equipment and insurance increased dramatically, there were corresponding drops in spending on books and other workers.
Teachers’ pay remained the highest cost, recording 50% of total spending in 2001, while other workers’ salaries fell from 28% in 1981 to 15% in 2001.
Expenditure on resources such as books increased to 20% by 1991 before decreasing to only 9% by the end of the period. In contrast, the cost of furniture and equipment decreased to 5% in 1991, but rose dramatically in 2001, reaching 23% of the total budget. It is worth noting that the spending on insurance four-folded from 2% in 1981 to 8% in 2001.